The wreckage of a Japanese mini-sub, destroyed at Pearl Harbor a little more than an hour before the December 7, 1941, attack, is explored. The two-man sub, destroyed by the USS Ward, was discovered in August 2002.

Exploring the wreckage of the USS Mississinewa, which was sunk near the Caroline Islands in 1944 by a Japanese torpedo manually guided on a suicide mission.

Exploring the wreckage of Duplex Drive Tanks that sank off the coast of Normandy during the D-Day invasion on June 6, 1944.

Exploring the World War II minesweeper YMS-304, which was sunk off the coast of Normandy a month after the D-Day invasion.

This episode explores a ferryboat that sank off the coast of Sicily in 1996.

It was the first submarine ever to sink an enemy ship, but after only one successful mission the H.L. Hunley vanished with its crew and lay hidden for more than a century. The circumstances surrounding the disappearance of the Confederacy’s secret weapon have remained an enduring mystery since the Civil War era, but now NGC has uncovered what may have brought it down.

June 20, 1941. The U.S. submarine O-9 noses below the surface off the coast of New Hampshire, carrying a crew of 33, and is never seen again. Years of inquiries have failed to find answers to what caused this terrible tragedy…until now. In this exciting program, join DEEP SEA DETECTIVES Richie Kohler and John Chatterton, as they head out to sea with the National Undersea Research Center to take the first-ever video survey of the O-9 wreck in an attempt to solve this long-forgotten mystery. First, travel to the U.S. Naval Submarine School in Groton, Connecticut, where the team learns about some of the potential emergencies and worst-case scenarios submariners face while submerged. Next, investigate evidence of structural deficiencies on the O-9 before it was returned to service for the war, which could point to an explanation for the tragedy. Finally, experience the thrill of an up-close look at wreck, which provides crucial clues as to what might have gone wrong.