This list contains the 5 most successful German U-boats during the First World War based on total tonnage. Only sunk commercial vessels are included, not military (warships) nor damaged ships.

In 1939, when the Second World War broke out, Germany had only managed to construct 57 U-boats, but these new U-boats were far sturdier and more technologically advanced than their WWI predecessors, featuring heat-seeking torpedoes, large gun decks, and spiderweb mines.

Here we’ll run through the five most successful U-boats that sailed in World War II, based on the total tonnage of ships they managed to sink.

The German military submarines known as U-boats that were in action during World War II were built between 1935 and 1944, and were numbered in sequence from U-1 upwards. Numbering was according to the sequence in which construction orders were allocated to the individual shipyards, rather than commissioning date; thus some boats carrying high ...

U-995. Those visiting Kiel, Germany can board and tour the U-995, a completely intact Type VIIC/41 U-boat. From September of 1943 to the end of the war, the 220-foot vessel conducted several patrols, sinking a total of nine enemy ships, including two warships.