The story starts with the weird oceanography of the Black Sea. A bunch of big rivers flow into this small sea, flooding it with fresh water and organic matter. The influx of fresh water causes the sea to divide into two distinct zones, with heavier, less saline water in the depths and a 200-meter deep layer of salty water on top. The vast amounts of organic matter mostly sink into the sealed depths. You may have read that when too much fertilizer and so on flows down rivers, a huge dead zone forms around the river mouths, where the excess phosphorus and nitrogen cause bacterial blooms that deplete all the oxygen. This has happened on a grand scale in the Black Sea. As a result the whole sea below about 200 meters is so low in oxygen as to be almost completely dead. In particular, none of the organisms that typically eat wooden shipwrecks are present.
Black Sea Maritime Archaeology Project. Exploring a section of the sea bottom claimed by Bulgaria, they have identified more than 40 shipwrecks, some of them exquisitely preserved. The picture above shows a section of an Ottoman wreck of the 18th century, with intact rope and elaborately carved wooden details.
combines photography with the careful measurement of distances between objects, letting a computer turn flat images into renderings that seem three-dimensional.These vessels are in water more than a mile deep, so exploring them will not be easy. But if rope is preserved, all sorts of other things might be, including documents, clothing, and bones.