The U-612 used during filming is a non-diving u-boat replica of the US Navy submarine S-33 built in Valetta, Malta. It was heavily modified but is the same watercraft used for U-571 (2000).
German submariners had the lowest survival rate of any branch of service of any country during World War Two. Of the some 40,000 men who served on U-boats, 33,000 were killed.
On August 4 1942, the real U-612 was accdentally rammed off Danzig by U-444 during trials after construction. She sank with the loss of two men. After refloating and repairs she was deemed unfit for front line action and so was used as a training submarine until the end of the war. On May 2, 1945 she was scuttled to avoid imminent capture by the Russians. She never saw action.
Renewed for a second season on December 6, 2018.