L'Atalante basin is a hypersaline brine lake at the bottom of the Mediterranean Sea about 192 km (119 mi) west of the island of Crete.

They were formed by Messinian evaporite salt deposits dissolving out of the Mediterranean Ridge and collecting in abyssal depressions about 3,000 m (9,800 ft) deep.

[5] The L'Atalante basin's salinity is near saturation at 365 g⁄L (about 8 times that of ordinary seawater), which prevents it from mixing with the oxygenated waters above; therefore, it is completely anoxic.

[5] In the brine, there are fewer cells; extremophiles predominate, including members of the deep-sea hydrothermal vent euryarchaeota (DHVEs), Methanohalophilus and Pseudomonadota (formerly Proteobacteria).

[6] The dark gray anoxic sediments at the bottom of L'Atalante lake are covered with a 1 cm (0.4 in) loose black layer.