Bathyscaphe Trieste
Trieste is a Swiss-designed, Italian-built deep-diving research bathyscaphe, which with its crew of two reached a record maximum depth of about , in the deepest known part of the Earth's oceans, the Challenger Deep, in the Mariana Trench near Guam in the Pacific. On 23 January 1960, Jacques Piccard (son of the boat's designer Auguste Piccard) and US Navy Lieutenant Don Walsh achieved the goal of Project Nekton.
Sarma cave
Sarma Cave (), located in Gagra District, Abkhazia, Georgia, is the third deepest recorded cave in the world. Its current depth (1830 m) was measured in 2012 by a team led by Pavel Rudko.