In the Caribbean archipelago, the rare pre-Columbian underwater remains identified to date are generally located at shallow depths on coastal margins such as the Los Buchillones site in Cuba, the Îlet Colas or the Îlet Chasse site in Guadeloupe. The new discoveries in the Grand Cul-de-Sac Marin are of a completely different nature. Following reports in 2012, surveys were organized: a sample of 160 lithic pieces scattered on the seabed between 2.50 m and 4 m deep was taken more than 1 km offshore. It is macrolithic tools in andesite. The most spectacular are axes blades and abrasive tools such as grinding stones, grinders, mortars and circular polishers. There are also elongated pebbles bearing percussion marks attesting to their use as hammers. The status of this vast deposit is still undetermined. It could result from the repetition over the centuries of marine accidents leading to cargo losses. Another hypothesis supposes that these artefacts come from camps or pre-Columbian villages installed on a paleo-littoral and whose vestiges were submerged by the sea following the post-glacial rise of the sea level, or because of great storms causing the erosion of the substrate. The hypothesis of submergence of pre-ceramic sites by rising sea level is reinforced by the discovery of a layer of peat around 5 m deep dated around 4000-5000 BC and containing remains of freshwater trees reflecting a terrestrial environment.