The Black Sea off of the coast of the Ukraine is unique in that it has a dense layer of stagnant, oxygen deprived water which blankets its lower depths referred to as the “anoxic layer”. This layer has preserved shipwrecks perfectly, and is thought to preserve human remains as well, although none have been found. Anything organic which should rot away like wood, leather, cotton etc. stays completely intact for thousands of years under these conditions. It is theorized that 7500 years ago, the Black Sea was a landlocked, freshwater lake which crossed over a thin strip of land referred to as the “Bosphorus”, as the world’s oceans began to swell due to melting glaciers. This caused seawater to flood into the Black Sea and because it was more dense than the freshwater already there, it sank it to bottom and settled. The saltwater was cut off from the oxygen supply which it would normally receive from ocean currents. The anoxic layer is approximately 183 meters deep and produces hydrogen sulfide as a byproduct which is poisonous to most living creatures including those which consume and break down ships