Task & Purpose has a terrific piece detailing how the USS Barb (SS-220) successfully “sank” a train — on the Japanese home islands, no less.
Max Hauptman writes:
The plan was relatively simple: Eight men would paddle ashore on two inflatable boats and plant an explosive charge along the rail line. Every member of the crew had volunteered, but given the risks of the mission, Fluckey selected them based on his own criteria — he wanted only unmarried men, and preferably those with some scouting experience.
Saunders, along with electrician’s mate Bill Hatfield, rigged a 55-pound bomb. It was made from a scuttling charge wired to three batteries and placed inside a pickle can. Hatfield also improvised a detonator that would be triggered by the weight of a train passing over it.
Shortly after midnight on July 23, 1945, the USS Barb surfaced 950 yards off the shore of Sakhalin, and the eight men, among them Saunders and Hatfield, set out. They had about three hours, as Fluckey told them that the submarine would have to submerge before dawn.
“Boys,” Fluckey told the men, according to the U.S. Naval Institute, “if you get stuck, head for Siberia 130 miles north. Follow the mountain ranges. Good luck.”
You can read the rest here.
One should never underestimate an American submariner’s ingenuity when provided explosives and a bit of time.