Interesting Maps

Most Japanese shipping was sunk by Submarines and Aircraft.

But the US was hampered by multiple faults on their Mark 14 torpedo until the end of 1943. And for a while from November 1942 the USS Enterprise was the only operational US carrier in the Pacific theatre. So most of that shipping was sunk in '44 and by '45 there wasn't much left.

If the Mark 14 worked then In April 1943 then USS Tuny could have taken out three Japanese carriers instead of damaging one, And the submarine attack on Tokyo could have caused a major panic.

American undersea craft killed at least 97,342 Japanese soldiers—more than the Marine Corps and the U.S. Army did in the central Pacific drive from Tarawa in November 1943 to Iwo Jima in February–March 1945. …

According to Japanese historian Sadae Ikeda, some 176,000 Japanese soldiers and paramilitary personnel perished in ships sunk from all causes over the course of the war.

The Japanese didn't use convoys until it was too late so unescorted ships faced American subs had radar and plenty of reports from codebreaking. Because the Japanese army and navy didn't get on they each had their own cargo shipping. So you had the crazy situation where empty ships were passing each other in opposite directions.

The UK and Germany also started the war with dodgy torpedoes, the Russians not so much but they didn't venture as far. The Japanese type 93 had a sensitivity adjuster and but they figured out very quickly that crews were getting premature detonations by setting them to be too sensitive and sorted that.

During the Falklands War the General Belgrano was sunk with Mark VIII torpedoes, a 1920's design that had been thoroughly debugged by then, rather than risk using the latest and greatest ones.