What is the deepest valley in the world?
Kali Gandaki Gorge
The Kali Gandaki Gorge or Andha Galchi is the gorge of the Kali Gandaki (or Gandaki River) in the Himalayas in Nepal. The Kali Gandaki gorge is the deepest gorge in the world, being lower than Annapurna I which bounds it at one point.
Woodingdean Water Well
The Woodingdean Water Well is the deepest hand-dug well in the world, at 390 metres (1285 feet) deep. It was dug to provide water for a workhouse. Work on the well started in 1858, and was finished four years later, on March 16, 1862. It is located just outside of Nuffield Hospital, in Woodingdean, UK.
Yarlung Tsangpo
The Yarlung Tsangpo Grand Canyon, formed by a horse-shoe bend in the river where it leaves the Tibetan Plateau and flows around Namcha Barwa, is the deepest, and possibly longest canyon in the world.
Walchensee
Walchensee or Lake Walchen is one of the deepest and largest alpine lakes in Germany, with a maximum depth of and an area of . The lake is south of Munich in the middle of the Bavarian Alps. The entire lake, including the island of Sassau, is within the municipality of Kochel. To the east and the south, the lake borders the municipality of Jachenau.
Jordan Valley
The valley is a long and narrow trough, it is long with a width averaging with some points narrowing to over most of the course before widening out to a delta when reaching the Dead Sea. Due to meandering the length of the river itself is . This is the deepest valley in the world, beginning at an elevation of below sea level and terminating at an elevation lower than below sea level. On both sides, to the east and west, the valley is bordered by high, steep, escarpments with the difference in elevation between the valley floor and the surrounding mountains varying between to .
Zacatón
Zacatón (El Zacatón sinkhole) is a thermal water-filled sinkhole belonging to the Zacatón system - a group of unusual karst features located in Aldama Municipality near the Sierra de Tamaulipas in the northeastern state of Tamaulipas, Mexico. It is the deepest known water-filled sinkhole in the world with a total depth of : the plus deep Pozzo del Merro (Sant'Angelo Romano, Latium Region, Italy) is deeper (actual depth yet unknown), but
Wasdale
Wasdale () is a valley and civil parish in the western part of the Lake District National Park in Cumbria, England. The River Irt flows through the valley to its estuary at Ravenglass. A large part of the main valley floor is occupied by Wastwater, the deepest lake in England (258 feet). The population of Wasdale was only minimal and, from the 2011 Census is included in the parish of Gosforth.
Dragon Hole
Dragon Hole is the deepest known underwater sinkhole (blue hole) in the world. It is deep. and is located about south of Discovery Reef in the Paracel Islands at . Blue holes are characteristically hundreds of metres deep and generate a distinctive blue colour when seen from above.
Adams River (British Columbia)
The headwaters of the Adams are several unnamed glaciers at roughly elevation in the north-east region of the Monashee Range of the Columbia Mountains. The upper portion of the river flows roughly south and southwest through wetlands and passes through two small lakes, Tumtum and Mica. It has sections of rapids and whitewater, and flows over cataracts below Tumtum Lake. Its flow drops by per kilometre in certain sections. After travelling for and entering the Shuswap Highland, it enters the northern end of Adams Lake. 
Adams Lake is roughly along its north-south axis, and reaches a maximum depth of , making it the 24th deepest lake in the world. The Lower Adams issues from the extreme southern end of the lake and travels through a narrow valley. It empties into Shuswap Lake near the community of Squilax. From Adams Lake to the Shuswap, the Lower Adams drops in elevation.
List of deepest mines
This list of deepest mines includes operational and non-operational mines that are at least , which is the depth of Veryovkina Cave, the deepest known natural cave in the world. The depth measurements in this list represent the difference in elevation from the entrance of the mine to the deepest excavated point.
Zhemchug Canyon
It has a vertical relief of dropping from the shallow shelf of the Bering Sea to the depths of the Aleutian Basin. Zhemchug Canyon is deeper than the Grand Canyon which is deep. It has two main branches, each larger than typical continental margin canyons such as the Monterey Canyon. What makes the Zhemchug Canyon the world's largest is not only its great depth, but its immense cross-sectional and drainage area, (11,350 km) and volume (5800 km).
Vikos Gorge
Vikos is listed as the deepest gorge in the world by the Guinness Book of Records among others.
Crater Lake
Crater Lake (Klamath: giiwas) is a crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The lake partly fills a nearly -deep caldera that was formed around 7,700 (± 150) years ago
by the collapse of the volcano Mount Mazama. There are no rivers flowing into or out of the lake; the evaporation is compensated for by rain and snowfall at a rate such that the total amount of water is replaced every 250 years. With a depth of , the lake is the deepest in the United States. In the world, it ranks ninth for maximum depth, and third for mean (average) depth.
Cave diving
Silfra is a fissure between the North American and Eurasian tectonic plates in Thingvellir National Park. It is the only place in the world where you can dive or snorkel directly in a crack between two tectonic plates. The tunnel from the entrance of Silfra to the cave is commonly known as ‘The Tunnel’, due to the strong current that ‘flushes’ divers attempting to swim through. This tunnel is rarely dived due to the dangerous head-first vertical dive needed to pass through. The deepest part of the cave is at least deep, and has only been dived by a few people because of the narrow and unstable passages.
Kyffhäuser
Today, the hills are a popular tourist site, featuring the restored medieval "Reichsburg Kyffhausen" complex, including a small museum and the castle well, at depth said to be "the deepest castle well in the world". The downhill "Pfalz" of Tilleda is an archaeological open-air museum and a stop on the scenic Romanesque Road.
Calumet and Hecla Mining Company
By 1897, the Calumet & Hecla's Red Jacket shaft had reached a vertical depth of 4,900 feet, making it the deepest mine in the world. The neighboring Tamarack mine became the world's deepest mine for some years; it was bought by Calumet & Hecla, and became part of the Calumet & Hecla system. The Tamarack/C&H remained the world's deepest mine until about 1915, when its vertical depth of 5,500 feet was exceeded by the 5,824-foot depth of the Morro Velho gold mine in Brazil.
Yellala Falls
The Yellala Falls ("Rapides de Yelala" or "Chutes Yelala"; also spelled as "Ielala") are a series of waterfalls and rapids on the Congo River just upstream from Matadi in the Democratic Republic of the Congo.
The falls are the lowest of a long series of rapids that render the river unnavigable, forcing colonial explorers to travel by foot as far as the Stanley Pool upstream.
The Congo is the third largest river in the world by volume of water discharged, and the deepest in the world. The section of river that ends with the Yellala falls has over 300 species of fish, many found nowhere else.
Tears of the Turtle Cave
Tears of the Turtle Cave is located in the Bob Marshall Wilderness in western Montana and is currently the deepest limestone cave in the United States since passing New Mexico's Lechuguilla cave in 2014. As of August 2016 the cave is known to be 1659 feet deep and 1.32 miles long. The cave consists mostly of roughly 2 foot wide fissure passage passing over dozens of short rope drops. With a mean temperature of 39 degrees F (4 C), it is muddy and poorly decorated.
Buckskin Gulch
The Buckskin Gulch, a canyon in southern Utah, is one of the main tributaries of the Paria River, which is itself a minor tributary of the Colorado River. It is the longest and deepest slot canyon in the southwest United States and may be the longest in the world. As such it is one of the premier destinations for slot canyon hikers, and receives a high amount of foot traffic.
Kinzig (Rhine)
The Kinzig valley is the deepest in the inner Black Forest. In the lower Kinzig valley the villages are below 200 metres above sea level. The climate in the valley is therefore milder than in most other areas of the Black Forest. In the lower valley fruit and wine are produced; Gengenbach, Ortenberg and Ohlsbach are well-known names of wine-growing villages, some of which are on the Baden Wine Road. The countryside around the Kinzig valley in spring blooms far earlier than the surrounding regions of the Black Forest.
Himalayan subtropical broadleaf forests
The ecoregion covers an area of and is bisected by the Kali Gandaki River, which has gouged the world's deepest river valley through the Himalayan Range. It forms a critical link in the chain of interconnected Himalayan ecosystems, where altitudinal connectivity between the habitat types is important for ecosystem function. The soil is composed of alluvium deposited over the ages by the rivers that drain this young mountain range.
Canyon
The Yarlung Tsangpo Grand Canyon (or Tsangpo Canyon), along the Yarlung Tsangpo River in Tibet, is regarded by some as the deepest canyon in the world at 5,500 m (18,000 ft). It is slightly longer than the Grand Canyon in the United States. Others consider the Kali Gandaki Gorge in midwest Nepal to be the deepest canyon, with a 6400 m (21,000 ft) difference between the level of the river and the peaks surrounding it.
Valley of Mexico
The Valley of Mexico is located in the Trans-Mexican Volcanic Belt.
The valley contains most of the Mexico City Metropolitan Area, as well as parts of the State of Mexico, Hidalgo, Tlaxcala and Puebla. The Valley of Mexico can be subdivided into four basins, but the largest and most-studied is the area which contains Mexico City. This section of the valley in particular is colloquially referred to as the "Valley of Mexico".
The valley has a minimum elevation of above sea level and is surrounded by mountains and volcanoes that reach elevations of over . It is an enclosed valley with no natural outlet for water to flow and a gap to the north where there is a high mesa but no high mountain peaks. Within this vulnerable watershed all the native fishes were extinct by the end of the 20th century. Hydrologically, the valley has three features. The first feature is the lakebeds of five now-extinct lakes, which are located in the southernmost and largest of the four sub-basins. The other two features are piedmont, and the mountainsides that collect the precipitation that eventually flows to the lake area. These last two are found in all four of the sub-basins of the valley. Today, the Valley drains through a series of artificial canals to the Tula River, and eventually the Pánuco River and the Gulf of Mexico. Seismic activity is frequent here, and the valley is considered an earthquake prone zone.
Arroyo Seco, Querétaro
The area’s location over the Huasteca Karst and the erosion of limestone has given rise to numerous pit caves. The largest of these in the Sierra Gorda is located in Arroyo Seco, called the Sótano de Barro, located in the Santa María de los Cocos community. The Sótano del Barro is one of the largest cavities of the world by volume, measuring 15 million cubic metres, surpassed only the Sima Mayor de Sarisariñama in Venezuela. In comparison, the Sótano de Las Golondrinas has a volume of only five million meters cubed. Its widest diameter measures 420 meters and its average width is 200 meters. It has a total depth of 455 meters with a direct drop of 410 meters. Its perimeter is surrounded by dense vegetation, which is a sanctuary for green macaws. It requires a walk or mule ride of about two hours through dense forest to reach. The walls of the pit cave are mostly vertical and partially covered by vegetation. At the bottom of the cave there is a small forest on a floor which was sea bed 100 million years ago, which measures 220 meters long and 100 meters wide. Despite its depth, the bottom of the pit cave receives an abundance of sunlight allowing for the growth of trees and other vegetation, making it an isolated mini forest. The bottom also has a number of small caves, with the largest fifty meters long. This pit cave has been classified as the deepest in the world although this has recently been challenged by those who wish to include those pit caves which are not continuous such as the Stary Swistak in Austria, which has a total depth of 480 meters.
Crater Lake
When considering the mean, or average depth of lakes, Crater Lake becomes the deepest lake in the Western Hemisphere and the third-deepest in the world. Crater Lake Institute Director and limnologist Owen Hoffman states "Crater Lake is the deepest, when compared on the basis of average depth among lakes whose basins are entirely above sea level. The average depths of Lakes Baikal and Tanganyika are deeper than Crater Lake; however, both have basins that extend below sea level."
Nereus (underwater vehicle)
The Challenger Deep is located in the Western Pacific Ocean near the island of Guam in the Mariana Trench, the deepest known part of an ocean on earth, and the deepest known location on earth. The May 2009 dive by the "Nereus" achieved a depth of , making it the world's deepest-diving vehicle then in operation, and the first since 1998 to explore the Mariana Trench. To accomplish this dive, the vehicle had to sustain pressures over 1,000 times the atmospheric pressure at the Earth's surface. It hovered over the trench for more than 10 hours and sent back live video to the mother ship.
Challenger Deep
The Challenger Deep is the deepest known point in the Earth's seabed hydrosphere, with a depth of by direct measurement from submersibles, and slightly more by sonar bathymetry. It is in the Pacific Ocean, at the southern end of the Mariana Trench near the Mariana Islands group. The Challenger Deep is a relatively small slot-shaped depression in the bottom of a considerably larger crescent-shaped oceanic trench, which itself is an unusually deep feature in the ocean floor. The Challenger Deep's bottom is about long and wide, with gently sloping sides. The closest land to the Challenger Deep is Fais Island (one of the outer islands of Yap), southwest, and Guam, to the northeast. It is located in the ocean territory of the Federated States of Micronesia, from its border with ocean territory associated with Guam.
Sinkhole
When sinkholes are very deep or connected to caves, they may offer challenges for experienced cavers or, when water-filled, divers. Some of the most spectacular are the Zacatón cenote in Mexico (the world's deepest water-filled sinkhole), the Boesmansgat sinkhole in South Africa, Sarisariñama tepuy in Venezuela, the Sótano del Barro in Mexico, and in the town of Mount Gambier, South Australia. Sinkholes that form in coral reefs and islands that collapse to enormous depths are known as blue holes and often become popular diving spots.
Morro Velho
In 1915, the Morro Velho mine reached a vertical depth of 5,824 feet, which made it the deepest mine in the world. The miners continued going deeper, and the mine kept the title of world’s deepest until 1928, when the Village Deep mine in South Africa reached a vertical depth of 8,000 feet, exceeding the depth of the Morro Velho, which was 7,126 feet in 1929.
Stak Valley
Stak Valley (, ) is a valley in the Roundu Subdivision of District Skardu, Gilgit-Balitistan, Pakistan. The valley is on the right bank of the Indus River, Pakistan's longest river, between Skardu and Giligit city. The valley is the biggest valley in term of area and population in Roundu subdivision. The valley has been one of the very important regions of the area in term of in history and of geological formation as well.
Saint-Léonard underground lake
Saint-Léonard underground lake (French "Lac souterrain de Saint-Léonard") is located at Saint Léonard in the canton of Valais, Switzerland. It is formed where a bed of Triassic gypsum, emplaced within impervious Carboniferous strata, has been dissolved by groundwater. With a length of 300 and a width of 20 m it is the largest underground lake in Europe. It was discovered in 1943 by Jean-Jacques Pittard. Prior to 1946 the water-level was much higher, but an earthquake with a force of 5.6 on the Richter-scale opened additional fissures in the cave on January 25, 1946 made it more readily navigable. Its water is constantly at . The lake is accessible by the public since 1949. Visits are organized daily from March 15 to November 1, from 9 am to 5 pm. The visit is about half an hour long, and is held in English, French, German and Italian. Ticket-prices are 10 CHF for adults and 5 CHF for children.
Mining
The largest underground mine is Kiirunavaara Mine in Kiruna, Sweden. With of roads, 40 million tonnes of annually produced ore, and a depth of , it is also one of the most modern underground mines. The deepest borehole in the world is Kola Superdeep Borehole at
Parlung Tsangpo
Parlung Tsangpo (; ), is a river in Nyingchi, Tibet, China. It is the largest tributary on the left side of Yarlung Tsangpo. Its source is the Arza Gongla Glacier, at an elevation of 4900m. It first flows north into Ngagung Tso, then turn northwest to Rakwa Tso. It joins Yarlung Tsangpo near Bomê. The total length is 266 km, and the drop of elevation is 3360m. The drainage basin covers an area of 28,600 km2. The lower part of Parlung flows through the Parlung Tsangpo Valley, which is among the deepest in the world.
Bailey–Morshead exploration of Tsangpo Gorge
In 1913 Bailey, an intelligence officer with the Indian Army, invited Morshead to be the surveyor in an expedition to explore the Yarlung Tsangpo Grand Canyon (Tsangpo Gorge), now known to be the world's deepest gorge.
Bailey and Morshead explored from the south with Morshead surveying the entire route and calculating the results as they went so as not to delay progress. By ascending the Dibang river and crossing the Yonggyap Pass () and the Himalayan watershed into Tibet, they reached the Dihang and started up the Gorge.
Chevé Cave
In 2004, an international caving expedition led by the U.S. Deep Caving Team discovered a new cave they named J2. The entrance of J2 located 5 kilometers northeast of the Chevé Cave entrance. J2 appears to head in the direction of Chevé Cave, with a predicted intersection beyond the tunnel collapse that stopped the team in 2003. Current expeditions are underway to find a connection between J2 and Chevé Cave, which will produce a cave system more than 2 kilometers in depth. The integration of the entire system will produce a 2,597 meter deep cave and would represent the deepest cave in the world.
Hells Gate State Park
Hells Gate State Park is a public recreation area located on the southern edge of Lewiston, Idaho, at the Snake River's downstream entrance to Hells Canyon, the deepest canyon in North America. The state park was created by the U.S. Army Corps of Engineers to mitigate the construction of the Lower Granite Dam; the Idaho Department of Parks and Recreation began leasing the site in 1973. The park's offer trails for hiking, mountain biking, and horseback riding as well as opportunities for camping, picnicking, fishing, boating, swimming, and taking jet boat trips into the canyon. The park sits at the lowest elevation of any Idaho state park, at above sea level.
Vorontsovka Caves
The Vorontsovskaya Cave System (Воронцовская система пещер) is a long chain of caves in the Khosta and Adler districts of Sochi, Russia. It is part of a range of Mesozoic limestones that runs parallel to the Black Sea coast for 400 km. and contains the Voronya Cave, the world's deepest cave.
Marine geology
The Mariana Trench (or Marianas Trench) is the deepest known submarine trench, and the deepest location in the Earth's crust itself. A subduction zone where the Pacific Plate is being subducted under the Philippine Sea Plate. The bottom of the trench is further below sea level than Mount Everest is above sea level.
Sierra de Tamaulipas
In the southeastern part of the Sierra in the municipality of Aldama, Tamaulipas is a limestone karst area in which many caves and cenotes (water-filled sinkholes) are found, including Zacatón which is the deepest sinkhole in the world with a depth of . In 1994, cave-diving pioneer Sheck Exley died attempting to dive to the bottom of Zacatón.
Tekezé River
The Tekezé or Täkkäze River (, originally meaning "river"), also spelled Takkaze, is a major river of Ethiopia. For part of its course it forms a section the westernmost border of Ethiopia and Eritrea. The river is also known as the Setit in Eritrea, western Ethiopia, and eastern Sudan. According to materials published by the Ethiopian Central Statistical Agency, the Tekezé River is long. The canyon which it has created is the deepest in Africa and one of the deepest in the world, at some points having a depth of over 2000 meters (6,562 feet).
East Rand Mine
East Rand Proprietary Mines (ERPM) is a 125-year-old underground gold mining operation on the Witwatersrand Basin at Boksburg, to the east of Johannesburg. The mine employed 3,850 people. It was the deepest mine in the world until 2008 at 3,585 metres depth, slightly more than the TauTona mine, also in South Africa, which was 3,581 metres at the time (in 2008 the TauTona mine completed a digging project that extended the depth of the mine by several hundred metres.)
Pierre Chevalier (caver)
Pierre Chevalier (24 April 1905 – 4 December 2001) was a well-known caver and mountaineer from France, with many alpine ascents and cave explorations to his credit. Chevalier is principally known for the exploration of the Dent de Crolles cave system over a twelve-year period (1936 – 1947), which became the deepest cave in the world. Chevalier recorded this exploration in his book "Escalades souterraines" ("Subterranean Climbers").
Zhemchug Canyon
Zhemchug Canyon is an underwater canyon located in the middle of the Bering Sea. This submarine canyon is the deepest and is tied for widest canyon in the ocean.
Deer Cave
Deer Cave was known as the largest cave passage in the world until the discovery of Sơn Đoòng cave in Phong Nha-Kẻ Bàng National Park in Vietnam. It is part of the Gunung Mulu National Park, a UNESCO World Heritage Site characterised by amazing caves and karst formations in a mountainous equatorial rainforest setting. 
The Clearwater cave, with approximately of known passages, is considered the longest cave system in Southeast Asia. It is recognised for its clear underground stream, popular with tourists. The Wind cave is located on the same trail leading to Clearwater cave, and is known for its blowing wind. It contains a chamber dubbed King’s Room, a cavern containing huge columns of stone on both the ceiling and the floor. The Lang cave is the smallest of the caves open to the public. However, its size allows up-close opportunities to see some of the common cave inhabitants such as bats and swiftlets.
Crater lake
A well-known crater lake, which bears the same name as the geological feature, is Crater Lake in Oregon. It is located in the caldera of Mount Mazama. It is the deepest lake in the United States with a depth of . Crater Lake is fed solely by falling rain and snow, with no inflow or outflow at the surface, and hence is one of the clearest lakes in the world.
Hollow Earth
Drilling holes does not provide direct evidence against the hypothesis. The deepest hole drilled to date is the Kola Superdeep Borehole, with a true vertical drill-depth of more than 7.5 miles (12 kilometers). However, the distance to the center of the Earth is nearly 4,000 miles (6,400 kilometers). Oil wells with longer depths are not vertical wells; the total depths quoted are measured depth (MD) or equivalently, along-hole depth (AHD) as these wells are deviated to horizontal. Their true vertical depth (TVD) are typically less than 4000 m.
Paleo Kathmandu Lake
Paleo Kathmandu Lake is the former lake (or lakes) which lied where Kathmandu Valley is today. Similar to the situation of Mexico City and Pokhara Valley, the valley where the lake once stood is densely populated, and highly vulnerable to both nearby and even distant earthquakes due to liquefaction and amplification of waves because of unsettled clay soil, specifically here called "kalimata". The valley has the world's worst quake risk.
Overdeepening
A tunnel valley is a large, long, U-shaped valley originally cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and formerly covering portions of all continents during past glacial ages. They range in size (up to 100 km in length and up to 4 km in width). Tunnel valleys exhibit classical overdeepening with maximum depths that may vary between 50 and 400 m; they vary in depth along the long axis. Their cross-sections exhibit steep sided flanks (similar to fjord walls) and flat bottoms typical of subglacial glacial erosion. Tunnel valleys were formed by subglacial erosion by water and served as subglacial drainage pathways carrying large volumes of melt water. They presently appear as dry valleys, lakes, seabed depressions, and as areas filled with sediment. If they are filled with sediment their lower layers are filled primarily with glacial, glaciofluvial or glaciolacustrine sediment, supplemented by upper layers of temperate infill. They can be found in areas formerly covered by glacial ice sheets including Africa, Asia, North America, Europe, Australia and offshore in the North Sea, the Atlantic and in waters near Antarctica.
Caves of Meghalaya
The Caves of Meghalaya comprise a large number of caves in the Jaintia, Khasi Hills and Garo Hills districts in the Indian state of Meghalaya, and are amongst the longest caves in the world. Of the ten longest and deepest caves in India, the first nine are in Meghalaya, while the tenth is in Mizoram. The longest is Krem Liat Prah in the Jaintia Hills, which is . The word "Krem" means cave in the local Khasi language.
Colca Canyon
Colca Canyon is a canyon of the Colca River in southern Peru, located about northwest of Arequipa. It is Peru's third most-visited tourist destination with about 120,000 visitors annually. With a depth of , it is one of the deepest in the world. The Colca Valley is a colorful Andean valley with pre-Inca roots, and towns founded in Spanish colonial times, still inhabited by people of the Collagua and the Cabana cultures. The local people maintain their ancestral traditions and continue to cultivate the pre-Inca stepped terraces, called andenes.
Lauterbrunnen
Lauterbrunnen lies at the bottom of a U-shaped valley that extends south and then south-westwards from the village to meet the Lauterbrunnen Wall. The Lauterbrunnen Valley ("Lauterbrunnental") is one of the deepest in the Alpine chain when compared with the height of the mountains that rise directly on either side. It is a true cleft, rarely more than one kilometre in width, between limestones precipices, sometimes quite perpendicular, everywhere of extreme steepness. It is to this form of the valley that it owes the numerous waterfalls from which it derives its name. The streams descending from the adjoining mountains, on reaching the verge of the rocky walls of the valley, form cascades so high that they are almost lost in spray before they reach the level of the valley. The most famous of these are the Staubbach Fall within less than one kilometres of the village of Lauterbrunnen. The height of the cascade is between , one of the highest in Europe formed of a single unbroken fall.
Veryovkina Cave
Veryovkina Cave (, ) is 2212 m deep and is the deepest-known cave on Earth. Its entrance is situated 2309 meters above sea level in Abkhazia, Georgia. The entrance of the cave has a cross section of , and is located in the Arabika Massif, Gagra Mountain Range of the West Caucasus, on the pass between the Krepost and Zont mountains, closer to the slopes of Mt. Krepost. The depth of the entrance shaft is 32 meters.
Kola Superdeep Borehole
In terms of true vertical depth, it is the deepest borehole in the world. For two decades it was also the world's longest borehole in terms of measured depth along the well bore, until it was surpassed in 2008 by the Al Shaheen oil well in Qatar, and in 2011 by the Sakhalin-I Odoptu OP-11 Well (offshore from the Russian island of Sakhalin).
Mendip Hills
The Hills conceal the largest underground river system in Britain; attempts to move from one cave to another through the underground rivers led to the development of cave diving in Britain. The first cave dive was attempted at Swildon's Hole in 1934, and the first successful dive was achieved the following year at Wookey Hole Caves, which has the deepest sump in Britain at 76 m (250 ft). The cave complexes at St. Dunstan's Well Catchment, Lamb Leer, and Priddy Caves have been identified as Sites of Special Scientific Interest.
The deepest cave in the Mendip Hills is Charterhouse Cave with a vertical range of .
Interandean Valles
The rugged topography of the Central Andes creates the warm, dry valleys that typifies the valles. Generally lying between 1,200 and 3,500 meters above sea level (m.a.s.l.) or 4,000 - 13,000 feet above sea level. Much of the area features steep hillsides and deep canyons, including the world's deepest canyon, the Colca Canyon.
Utladalen Landscape Protection Area
Utladalen Landscape Protection Area () is adjacent to Jotunheimen National Park, covering Utladalen, Norway's deepest valley. It is located about northeast of Øvre Årdal in the municipality of Årdal in Sogn og Fjordane, Norway.
Colca Canyon
In May 1981, the Polish Canoandes rafting expedition led by Jerzy Majcherczyk, made the first descent of the river below Cabanaconde, and proclaimed the possibility of its being the world's deepest canyon. It was so recognized by the Guinness Book of Records in 1986, and a National Geographic article in January 1993 repeated the claim. The joint Polish/Peruvian "Cañon del Colca 2005" expedition verified the altitudes of the river and the surrounding heights via GPS.
Cave del Valle (Cantabria)
Cave del Valle (, "The Valley's Cave"), locally also known as "La Viejarrona" (Old Girl), is located near "El Cerro Village" in the municipality of Rasines in Cantabria, northern Spain. The cave is the source of the "Silencio River", a tributary of the "Rio Ruahermosa", which in turn is a tributary of the "Asón River". Notable for its prehistoric, but particularly for its speleologic significance as it is recognized as one of the longest cavities in the world. The site is very popular among cavers, who have explored a total of over so far.
Kazumura Cave
Kazumura Cave is a lava tube and has been surveyed at 40.7 miles (65.5 km) long and 3,614 feet (1,102 m) deep making it the longest and deepest lava tube in the world. The cave is located on the island of Hawaiʻi on the eastern slope of Kīlauea. Kīlauea is the most recently active volcano on the Big Island. The ʻAilāʻau lava flow that contains Kazumura Cave originated from the Kīlauea Iki Crater about 500 years ago.
Bay of Bengal
Swatch of No Ground is a 14 km-wide deep sea canyon of the Bay of Bengal. The deepest recorded area of this valley is about 1340 m. The submarine canyon is part of the Bengal Fan, the largest submarine fan in the world.
Krubera Cave
In January 2001, the Ukr.S.A. expedition explored the cave to making it the deepest cave in the world. For the first time in the history of speleology, the deepest cave in the world had been established outside of western Europe. Since 2001, the Krubera explorations by the Ukr.S.A. have been undertaken within the frame of the multi-year project named "The Call of the Abyss", coordinated by A. Klimchuk, Y. Kasyan, G. Samokhin and K. Markovskoy. Besides the Ukrainian speleologists, cavers from many countries such as France, Spain, Russia, Moldova, Bulgaria, United Kingdom, Ireland, Israel and Lithuania have taken part in different expeditions of the Ukr.S.A.
Voyage to the Bottom of the Sea
Two milestones in underwater exploration were achieved in 1960, the year before "Voyage to the Bottom of the Sea" was released. On January 23, 1960, Jacques Piccard and Lieutenant Don Walsh (USN), in the bathyscaphe "Trieste", made the first descent to the bottom of the Challenger Deep. The Challenger Deep is the deepest surveyed spot in the world's oceans, and is located in the Mariana Trench, southwest of Guam. From February 16, 1960, to May 10, 1960, the submarine , under the command of Captain Edward L. Beach, Jr., made the first submerged circumnavigation of the world. "Triton" observed and photographed Guam extensively through her periscope during this mission, without being detected by the U.S. Navy on Guam.
Cave of Swallows
The Cave of Swallows, also called the Cave of the Swallows (), is an open air pit cave in the Municipality of Aquismón, San Luis Potosí, Mexico. The elliptical mouth, on a slope of karst, is 49 by 62 m wide and is undercut around all of its perimeter, widening to a room approximately 303 by 135 meters (994 by 442 ft) wide. The floor of the cave is a 333-meter (1092 ft) freefall drop from the lowest side of the opening, with a 370-meter (1,214 ft) drop from the highest side, making it the largest known cave shaft in the world, the second deepest pit in Mexico and perhaps the 11th deepest in the world.
Fernand Petzl
Petzl lived most of his life in the village of Saint-Ismier (near Grenoble), France at the foot of the mountain Dent De Crolles. He first went caving in Trou du Glaz in 1933, and was immediately captivated by the idea of exploring beyond the cave's known limits. Subsequent explorations there with Pierre Chevalier, Charles Petit-Didier and others culminated in connections to other caves in the massif, forming the Réseau de la Dent de Crolles which, in 1947, became the deepest cave in the world. Petzl also participated in explorations in the Gouffre Berger, which set a new world depth record in 1956 as the first cave deeper than 1000 metres (-1122m). Petzl was a proponent of cave explorations by small teams, an innovation at the time.
Sima Pumacocha
Sima Pumacocha (possibly from Spanish "sima" deep and dark cavern/abyss, Quechua "puma" cougar, puma, "qucha" lake) is a limestone cave located in the Lima Region, Yauyos Province, Laraos District, in central Peru near the village of Laraos, high in the Andes mountains. At 638 meters deep, it held the record for deepest known cave in South America from 2001 to 2006 when it was surpassed by Abismo Guy Collet. With the entrance being 4372 meters above sea level and the depth being over 500 meters, it is the highest major cave in the world. and It is located at .
Lake Manly
Lake Manly formed in Death Valley, a tectonic depression framed by the Cottonwood Mountains and Panamint Range to the west, Owlshead Mountains to the south and Black Mountains, Funeral Mountains and Grapevine Mountains to the east. Death Valley is about long and wide and consists of three basins: Badwater Basin which reaches a depth of beneath sea level, Cottonball Basin and Middle Basin. The Badwater Basin is the deepest point in North America. Death Valley began forming about 14 million years ago, and by the Pliocene it was well developed. The valley remains deep due to vertical faulting, which occurs faster there than anywhere else in the US. Various types of rocks form the surface areas of Death Valley, some going back as far as the Precambrian.
Quechee Gorge
The Quechee Gorge is located in Quechee, Vermont along U.S. Route 4. The gorge is 165 feet deep and is the deepest gorge in Vermont. It serves as a popular tourist attraction in Quechee State Park and can be viewed from the U.S. Route 4 bridge and from trails on both sides of the gorge. The Ottauquechee River flows through the bottom of the gorge and is a popular whitewater kayak run.
Lamprechtsofen
Lamprechtsofen (also called Lamprechtshöhle or, together with a connected cave, Lamprechtsofen-Vogelschacht) is a limestone karst river cave in Austria. With a depth of , it is one of the deepest caves in the world. Before the discovery of the Krubera Cave in Georgia, it was the deepest-known cave in the world. Lamprechtsofen is located northwest of Weißbach bei Lofer (Salzburg), Austria, in the Leogang Mountains.
Canyon
The Grand Canyon of northern Arizona in the United States, with an average depth of 1,600 m (one mile) and a volume of 4.17 trillion cubic metres, is one of the world's largest canyons. It was among the 28 finalists of the New7Wonders of Nature worldwide poll. (Some referred to it as one of the 7 natural wonders of the world.)
Pierre Chevalier (caver)
Chevalier first visited the Trou du Glaz entrance in 1935, and was struck by the possibility of exploring beyond what was at the time considered technically possible. With Fernand Petzl, Charles Petit-Didier and others, Chevalier completed explorations that connected four entrances (Trou du Glaz, Guiers Mort, P40 and Grotte Annette) and established the Dent de Crolles as the deepest cave system in the world (-658m).
Georgia (country)
The Krubera Cave is the deepest known cave in the world. It is located in the Arabika Massif of the Gagra Range, in Abkhazia. In 2001, a Russian–Ukrainian team had set the world depth record for a cave at . In 2004, the penetrated depth was increased on each of three expeditions, when a Ukrainian team crossed the mark for the first time in the history of speleology. In October 2005, an unexplored part was found by the CAVEX team, further increasing the known depth of the cave. This expedition confirmed the known depth of the cave at .
Eiksund Tunnel
The Eiksund tunnel () is an undersea tunnel in Møre og Romsdal county, Norway, which runs under the Vartdalsfjorden connecting Ørsta Municipality and Ulstein Municipality. The tunnel is long and reaches a depth of , which makes it the deepest undersea tunnel of its kind in the world.
Grand Canyon
The Grand Canyon is a river valley in the Colorado Plateau that exposes uplifted Proterozoic and Paleozoic strata, and is also one of the six distinct physiographic sections of the Colorado Plateau province. It is not the deepest canyon in the world (Kali Gandaki Gorge in Nepal is much deeper). However, the Grand Canyon is known for its visually overwhelming size and its intricate and colorful landscape. Geologically, it is significant because of the thick sequence of ancient rocks that are well preserved and exposed in the walls of the canyon. These rock layers record much of the early geologic history of the North American continent.
Abyssal plain
The Challenger Deep is the deepest surveyed point of all of Earth's oceans; it is at the south end of the Mariana Trench near the Mariana Islands group. The depression is named after HMS "Challenger", whose researchers made the first recordings of its depth on 23 March 1875 at station 225. The reported depth was 4,475 fathoms (8184 meters) based on two separate soundings. On 1 June 2009, sonar mapping of the Challenger Deep by the Simrad EM120 multibeam sonar bathymetry system aboard the R/V "Kilo Moana" indicated a maximum depth of 10971 meters (6.82 miles). The sonar system uses phase and amplitude bottom detection, with an accuracy of better than 0.2% of water depth (this is an error of about 22 meters at this depth).
Ayo Akinwolere
Blue Peter presenter Ayo Akinwolere has set two world records for swimming in one of the deepest stretches of water on the planet. Mr Akinwolere swam five miles across the Palau Trench, an 8,000-metre deep abyss in the Pacific Ocean. He is the first person to swim across the deepest part of the trench, and now holds the record for the deepest location for an open water swim. He took three and a half hours to complete his swim. His records were verified by the World Open Water Swimming Association. Until a few weeks before, Mr Akinwolere was unable to swim a length and was terrified of open water.
He said: "It's an absolute triumph to have completed this swim, after having had just over 10 weeks of swimming training I still cannot believe how far I've come.
"I could not swim a length before this and now I have swum over one of the deepest parts of the world.
"All the hours of gruelling training will be worth it if my challenge inspires more children from ethnic minorities to learn to swim."
Jomsom
A trail passes through the Lower Mustang region of Nepal, ending at the village of Kagbeni, a Tibetan influenced village filled with prayer wheels, chortens and a Buddhist monastery. The trail follows the Kali Gandaki River which forms the deepest ravine in the world; on one side lies the Annapurna mountain range and on the other side is Dhaulagiri. Between the two ranges, there are views of 8 of the 20 highest mountains in the world. The Kali Gandaki is a quarter of a mile wide river bed; during the winter the river will be dry, but during the summer and monsoon it fills with rain water and melting snow. The scenery of the trail ranges from forests of bright Rhododendrons (Nepali: लालीगुँरास) to rocky cliffs and desert. The culture along the track is a rich Combination of Hindu and Tibetan Buddhism. The trail's highest point is Muktinath at 3800 m, a holy site of temples sacred to both Buddhists and Hindus for centuries.
Scientific drilling
Like probes sent into outer space, scientific drilling is a technology used to obtain samples from places that people cannot reach. Human beings have descended as deep as 2,080 m (6,822 ft) in Voronya Cave, the world's deepest known cave, located in the Caucasus mountains of the country of Georgia. Gold miners in South Africa regularly go deeper than 3,400 m, but no human has ever descended to greater depths than this below the Earth's solid surface. As depth increases into the Earth, temperature and pressure rise. Temperatures in the crust increase about 15°C per kilometer, making it impossible for humans to exist at depths greater than several kilometers, even if it was somehow possible to keep shafts open in spite of the tremendous pressure.
Lake Malawi National Park
Lake Malawi is in the Great Rift Valley. The lake is above sea level and, with a depth of in places, is one of the deepest lakes in the world. Lake Malawi National Park consists of approximately of land and water at the southern end of the lake. The park includes most of the Nankumbu Peninsula, a mountainous headland that projects northwards into the lake terminating in Cape Maclear, the surrounding areas of water, and nine rocky islands close offshore. The peninsula rises steeply from the foreshore to the Nkhunguni Peak in the west and the Dzimwe Peak in the east. The slopes are clad in dense forests. There are few inhabitants on the mountainous part of the peninsula, but there are several fishing villages on the more level parts of the foreshore, the largest being Chembe, close to Cape Maclear. These villages are inside the park but are not part of it.
Gourgouthakas
Gourgouthakas (; from "small cutting on rocks, in which rain water is collected and from which animals drink water") is a cave located in the Lefka Ori mountains on the Greek island of Crete. It is the deepest cave in Greece, with an explored depth of , and is the 43rd deepest in the world.
Gagra Range
The range is mostly made up of limestone, with pronounced karst topography and is characterized by many deep canyons created by rivers. The deepest cave in the world, the Veryovkina Cave, is located in the Arabika Massif of the Gagra Range.
Vikos–Aoös National Park
Vikos Gorge is located on the southern slopes of mount Tymfi. Its main part is located between the villages of Vikos and Monodendri and attains a depth of about , with a southeast-northwest direction. The landscape of the long gorge, which belongs to the park's core zone, presents a diverse relief and is characterized by abrupt changes in altitude. At one point the gorge measures deep and wide from rim to rim, and as a result is listed by the Guinness Book of Records as the deepest canyon in the world in proportion to its width, though some gorge lobbyists contest that claim. Steep slopes and precipitous rocky cliffs dominate in the middle and higher zones respectively. Numerous gullies dissect both sides of the gorge and the weathering action of water down its walls creates extended screes.
Deepsea Challenger
Deepsea Challenger (DCV 1) is a deep-diving submersible designed to reach the bottom of Challenger Deep, the deepest-known point on Earth. On 26 March 2012, Canadian film director James Cameron piloted the craft to accomplish this goal in the second manned dive reaching the Challenger Deep. Built in Sydney, Australia by the research and design company Acheron Project Pty Ltd, "Deepsea Challenger" includes scientific sampling equipment and high-definition 3-D cameras, and reached the ocean's deepest point after two hours and 36 minutes of descent from the surface.
Tiger Leaping Gorge
At a maximum depth of approximately 3,790 meters (12,434 feet) from river to mountain peak, Tiger Leaping Gorge is one of the deepest and most spectacular river canyons in the world. The inhabitants of the gorge are primarily the indigenous Naxi people, who live in a handful of small hamlets. Their primary subsistence comes from grain production and hikers.
Utladalen
Utladalen is Norway's deepest valley. The main valley, when measuring from Øvre Årdal is long and is surrounded by dozens of mountain peaks that are all more than in height. From Øvre Årdal, a comfortable walking road has been constructed, funded by voluntary contributions. The road passes through Vetti and crosses the Utla river on four spectacular bridges. The walking path ends at one of Norway's tallest waterfalls, Vettisfossen.
Rupse Falls
Rupse Falls has tremendous beauty around it. Deepest gorge in the world Kali Gandaki Gorge and Kali Gandaki river is nearly situated to this fall.
Geography of Abkhazia
The world's deepest known cave, Krubera (Voronja) Cave, is located in Abkhazia's western Caucasus mountains. The latest survey (as of September 2007) has measured the vertical span of this cave system as between its highest and lowest explored points.
Henry Morshead
In 1913 Frederick Bailey, an intelligence officer with the Indian Army, invited Morshead to be the surveyor in an expedition to explore the Yarlung Tsangpo Grand Canyon (Tsangpo Gorge), now known to be the world's deepest gorge.
Bailey and Morshead explored from the south with Morshead surveying the entire route and calculating the results as they went so as not to delay progress. By ascending the Dibang River they crossed the Himalayan watershed into Tibet to reach the Dihang River and ascending the Gorge.
Grassy Cove
Grassy Cove is drained entirely by underground streams. The valley's main stream, Grassy Cove Creek, flows northward across the cove before dropping into Mill Cave on the slopes of Brady Mountain. Dye traces indicate that it flows south through a series of caves before reemerging at the head of the Sequatchie Valley at Devilstep Hollow Cave, where it forms the headwaters of the Sequatchie River. Grassy Cove Saltpeter Cave, located on the eastern slope of Brady Mountain, is the thirteenth longest cave in Tennessee and one of the 100 longest caves in the United States. Other caves in the cove include Windlass Cave, Bristow Cave, Mill Cave, Run to the Mill Cave, and Milksick Cave.
Canyon
Vying for deepest canyon in the Americas are the Cotahuasi Canyon and Colca Canyon, in southern Peru. Both have been measured at over 3500 m (12,000 ft) deep.
Velebit
There are hundreds of "holes" on Velebit. It has the largest and deepest caves in Croatia. The three-part "Lukina jama" cave is 1392 m deep, making it one of the deepest caves in the world, and the deepest in southeast Europe, while the "Slovačka jama" is 1320 m. What makes it unique is that it is completely vertical, steepest in the world. At the bottom of the pothole is a water course or siphon with branches that are still unexplored. A kind of leech was discovered in the pothole, which has been ascertained to represent a new species, genus and family; it has been named "Erpobdella mestrovi".
West Manggarai Regency
Sano (means Mount) Nggoang is 513 hectares (1.9 sq. mi.) of volcanic crater lake with depth of around 600 meters (1968.5 ft.), the deepest lake of its kind in the world.
Seikan Tunnel
The Seikan Tunnel is the world's longest tunnel with an undersea segment (the Channel Tunnel, while shorter, has a longer undersea segment). It is also the second deepest and the second longest main-line railway tunnel after the Gotthard Base Tunnel in Switzerland opened in 2016.
Alessia Zecchini
She is currently the "deepest woman in the world" with her -105 meters CWT (Monofin) reached in San Andres Island in 2018. She reclaimed this record which she briefly lost to Hanako Hirose days before, on 10 May 2017.
Tumlingtar
Tumlingtar (टुम्लिङटार) is a region and a city, in Eastern Nepal, between the Arun and Sabha Rivers in Kosi Zone Provision NO 1. It is also the deepest valley and largest "ṭār" (butte or mesa) of Nepal. It is situated at 27.30 N, 87.20 E. Its elevation is 285 meters.
Lake Baikal
Lake Baikal is the largest freshwater lake by volume in the world, containing 22–23% of the world's fresh surface water. With of fresh water, it contains more water than the North American Great Lakes combined. With a maximum depth of , Baikal is the world's deepest lake. It is considered among the world's clearest lakes and is considered the world's oldest lake – at 25–30 million years. It is the seventh-largest lake in the world by surface area.
Douglas C. Gordon
In 1998, Gordon participated in an expedition to the Tibetan river Tsangpo (named the Brahmaputra River in its lower course), sponsored by National Geographic. The team of middle-aged paddlers also included the brothers Jamie McEwan (Olympic slalom bronze medalist in 1972) and Tom McEwan (former slalom racer, with first descent experience including the Great Falls of the Potomac), and Roger Zbel. Three of them would use expedition kayaks, one a whitewater canoe. Gordon was the most experienced of the team, but all were considered expert river runners. A ground crew of five completed the expedition. Their plan was to accomplish the first descent of a 140-mile (225 km) section of the Tsangpo, passing the deepest river gorge on earth, the more than 4877 meter (16,000 ft) deep gorge between 7782-meter Namjagbarwa Feng and 7194-meter Gyala Peri. The paddlers had planned up to six weeks for the descent.
Geography of Nepal
The "Gandaki/Narayani" has seven Himalayan tributaries in the center of the country: "Daraudi", "Seti Gandaki", "Madi", "Kali", "Marsyandi", "Budhi", and "Trisuli" also called "Sapta Gandaki". The "Kali Gandaki" rises on the edge of the Tibetan Plateau and flows through the semi-independent Kingdom of Mustang, then between the 8,000 meter "Dhaulagiri" and "Annapurna" ranges in the world's deepest valley. The Trisuli rises north of the international border inside Tibet. After the seven upper tributaries join, the river becomes the "Narayani" inside Nepal and is joined by the "(East) Rapti" from Chitwan Valley. Crossing into India, its name changes to "Gandak".
Department of Arequipa
The Colca Canyon, twice as deep as the Grand Canyon in the United States, is situated in the province of Caylloma. The Cotahuasi Canyon is in the La Union Province. Colca Valley provides incredible close-up views of majestic Andean condors soaring in their natural habitat. Cotahuasi, at , is thought to be the deepest canyon in the world. Both canyons offer spectacular scenery and villages as yet unaffected by the modern world.
Krubera Cave
Krubera Cave (; Also known as Voronya Cave, sometimes spelled Voronja Cave) is the second deepest known cave on Earth after the Veryovkina Cave. It is located in the Arabika Massif of the Gagra Range of the Western Caucasus, in the Gagra district of Abkhazia, a breakaway region of Georgia, currently under Russian occupation.
Qaqa Mach'ay
Located in the Yauyos Province of the Lima Region in central Peru, Qaqa Mach'ay (Quechua for "rock cave") is a limestone cave high in the Andes Mountains that was explored and surveyed in 2004 by an international expedition. At 4,930m above sea level, it is the highest surveyed cave in the world. The entrance to the cave is in the mountain named Wamp'una.
Mullins Valley
Mullins Valley () is a four mile long valley located at 5,400 ft elevation in the McMurdo Dry Valleys. It is one of the few dry valleys in the world to contain rock glaciers. US Antarctic Program (USAP) research has dated the subsurface ice in Mullins Valley at 4 million years old making it among the oldest ice on earth. United States Antarctic Program (USAP) research has also shown the rock glaciers in the valley to be analogous to the Arsia Mons region on Mars. Named for Jerry L. Mullins, Physical Scientist, Director, Polar Programs, Antarctic and Arctic Program for United States Geological Survey (USGS), National Science Foundation Antarctic geophysical research, and U.S Scientific Committee (SCAR) delegate to SCAR SCAGI committee. Appointed by the National Academy of Sciences, Polar Research Board. His was responsible for Antarctic field research in the Transantarctic Mountains, McMurdo Dry Valleys, Shackleton Mountains, Beardmore Mountains, Antarctic Peninsula, Mount Siple, Amundsen-Scott South Pole station and at deep field research locations in West Antarctica. His program conducted research in the disciplines of global positioning systems, geodesy, crustal motion, glacial geophysics, airborne geospatial systems, airborne geophysics, seismology, light radar (lidar), topographic mapping and he managed the USGS South Pole winter-over program from 1989 to 1994. He was appointed by the National Academy of Sciences, Polar Research Board as a US delegate to the Scientific Committee on Antarctic Research Geosciences Standing Scientific Group from 1995–July 2012 and was appointed as a member of the Advisory Committee on Antarctic Names in 1994. Mullins Valley appears in the Antarctic research literature, on the maps from the British expedition of Captain Scott and in aerial photographs from the United States expedition Operation Highjump by Admiral Byrd. Mullins Valley, Mullins Lake, Mullins Glacier, and Mullins Geodetic Station, Antarctica are named for United States polar explorer and researcher Jerry L. Mullins.