The U-20 was one of six German submarines built by Nazi Germany during World War II and deployed against the Soviet Union in the Black Sea. As part of Germany’s naval operations in the Black Sea, the submarine was deliberately scuttled by its crew off the coast of Karasu, Sakarya Province toward the end of the war, where it remains as a wreck today. U-20 is considered one of the rare WWII submarine remnants in Turkish territorial waters.
U-20 Sunken Submarine (T.C. Karasu Municipality)
History and Wartime Service
Initially, U-20 belonged to a class of submarines operating in the North Sea against British ships. One of Germany’s first naval victories occurred when U-23, under the command of Otto Kretschmer, sank a British vessel off the Shetland Islands. After Germany’s 1941 invasion of the Soviet Union, a naval campaign was planned in the Black Sea to target the Soviet fleet. Due to Türkiye’s neutrality and the denial of Bosporus passage, Germany had to find alternative transport routes. Six submarines, including U-20, were dismantled in Kiel, transported via the Elbe River to Dresden, moved by land to Ingolstadt, and then sent down the Danube River to Constanța Port, Romania. This extraordinary transfer covered approximately 3,300 km. U-20 and the other submarines were active in the Black Sea from October 27, 1942, to August 25, 1944, conducting numerous operations against Soviet ships. During this period, U-9, U-18, and U-24 were sunk by the Soviet Navy. When Romania declared war on Germany in August 1944, U-20, U-23, and U-19 were cut off from resupply and base support. Adolf Hitler offered to sell these submarines to Türkiye, but President İsmet İnönü declined, citing the act as a potential cause for war.
Scuttling and Discovery
Following Romania’s shift in allegiance, German authorities ordered the scuttling of U-20. In 1944, the crew deliberately sank the submarine off Karasu, Sakarya Province. The wreck lies approximately 2.5 km offshore, with a conning tower depth of 18 meters and a seabed depth of 23 meters. The submarine rests at a 35-degree list to port, measuring 42.7 meters in length, 4.1 meters in width, and weighing about 270 tons. The open torpedo hatches and periscope indicate that the crew left the submarine after scuttling. The wreck was first discovered in July 1994 during a Turkish Navy exercise off Karasu. The find was publicly reported in 2008 by the Sunday Telegraph. Since then, research and diving activities have made the site an attractive location for underwater tourism in Türkiye.
Diving and Conservation Efforts
U-20 is not classified as a war grave, as the crew evacuated safely. Diving is permitted, and the wreck is particularly interesting to military historians and underwater enthusiasts. In the 2020s, the Ministry of Agriculture and Forestry – Directorate of Fisheries and Aquaculture conducted cleanup operations on U-20, removing ghost nets, fishing lines, and abandoned gear with professional divers. This effort was coordinated by the Sakarya Governorship, Karasu District, Coast Guard Command, IC Karasu Port Authority, and Provincial Directorate of Agriculture and Forestry.
The Undersea Covered in Mussels (AA)
The Undersea Covered in Mussels (AA)
Significance
U-20 is one of the rare intact WWII submarines in the Black Sea. Its shallow depth allows for easy underwater exploration, making it a valuable resource for military history, maritime studies, and archaeology.
