Longest journey overland by a submarine

The location, in 2007, of three German submarines from the second world war scuttled in the Black Sea, has highlighted a remarkable feat of wartime transportation. The submarines, including one U-23 that was originally commanded by Otto Kretschmer (Germany), were located by a Turkish marine engineer, Selçuk Kolay. The route through the Bosporus river to the Black Sea was not open to the Germans during World War II (due to Turkish neutrality), so instead, six submarines belonging to the German Navy’s 30th Flotilla were taken by road and river from the German Baltic port of Kiel to Constanta, the Romanian Black Sea port (finally arriving there in May 1942) - a journey of 2,320 km (2,000 miles). The submarines were partially dismantled and loaded onto shallow draught pontoons in Kiel, taken by canal to the River Elbe and upstream to Dresden where they were transferred to low-bed motorised trailers and taken 300 miles to Ingolstadt by road. They were then ferried downstream to Constanta. The aim was to attack Russian shipping in the Black Sea and, in the two years they operated there, they sank dozens of ships for the loss of three submarines. In 1944, however, Romania switched to the Allies and this left the boats stranded with no way out of the Black Sea, as the Bosporus and Dardanelles were closed to them and they had no base from which to operate. The crews were ordered to scuttle the boats out of sight of the Turks. This they did and the boats location has remained a mystery until now.