Calypso Deep is the deepest point in the Mediterranean Sea, located in the Hellenic Trench in the Ionian Sea, 62.6 km south-west of Pylos, Greece, with a maximum depth of approximately 5200 m. It lies at about 36.56667°N, 21.13333°W.

Crewed descents

The first crewed descent into Calypso Deep was on 27 September 1965 by Captain Gérard Huet de Froberville, Dr. Charles "Chuck" L. Drake (USA), and Henri Germain Delauze in the French bathyscaphe Archimède. Drake, Froberville, and Delauze reported a maximum depth of 5110 m without a reference to the measurement accuracy. In January 2020, Caladan Oceanic commenced its second year of deep diving with the deep-submergence vehicle Limiting Factor, piloted by Victor Vescovo. The first dives of the 2020 season commenced with dives to the French submarine Minerve in the Mediterranean Sea on 1–2 February 2020, and the second crewed descent to the Calypso Deep. On 10 February 2020 Victor Vescovo and Prince Albert II of Monaco reached the bottom of the Calypso Deep at a newly calculated depth of 5109 m ±1 m using multiple direct measurement sensors. The 2020 expedition validated that the French mission in 1965 had, in fact, reached the deepest point of the Mediterranean Sea which, until this point, was not affirmed.