Abismo Guy Collet
The Abismo Guy Collet (SP-090) is the deepest cave in South America, and the deepest in the world that is formed in quartzite. Located in a tepui in northern Brazil near the border with Venezuela, this cave was first explored by cavers in 2006 to a depth of 671 meters.
North West Highlands Geopark
The area contains a number of limestone caves. The most well known of these is Smoo Cave, a large sea cave near Durness. This cave is unique within the UK in that its outer chamber was formed by the action of seawater, while the inner chambers were formed by fresh water. Its entrance 15 metres high, is the largest entrance of any sea cave in the British Isles. Archaeological excavations have found evidence of human habitation dating back to the Mesolithic period. The cave became well known after Sir Walter Scott visited it in 1814. Another notable cave site is the Inchnadamph Bone Caves. At these caves, remains of Eurasian lynx, brown bear, Arctic fox, reindeer and polar bears have been found; as well as human remains dated between 4,515 and 4,720 years old. Uamh an Claonaite, Scotland's longest cave is partly located below these Bone Caves.