Just weeks before WW2 ended, the USS Indianapolis violently sank, and 900 sailors were stranded at sea with no rescue in sight. For five days, they fought off exposure and shark attacks in the worst disaster at sea in U.S. naval history.

Undersea explorers aboard the research vessel Petrel detect a wreck off the coast of the Philippines that fits the profile of an American destroyer. Could it be the wreck of the USS Ward, the ship that fired America's first shot of WW2 at Pearl Harbor?

The USS Lexington birthed naval aviation and was victorious in the first carrier-to-carrier battle during WWII. Hours later, it erupted in flames due to enemy fire. Now, after 80 years, the Petrel hopes to spot the wreck and the storied planes that went down with her.

The Petrel team searches for the American aircraft carrier USS Hornet. The Doolittle Raid was launched off her deck to avenge Pearl Harbor. But six months later, the ship's life was cut short when the Hornet sailed into a hornet's nest of Japanese ships.

What happened aboard the USS Juneau would inspire the film "Saving Private Ryan." Five brothers were lost, but not all perished when the ship went down. At least one brother was among scores of men stranded at sea for eight horrifying days.

In one night, over one thousand Allied sailors died when four cruisers went down in flames. They rest in a graveyard littered with so many ships that it has become known as "Iron Bottom Sound." Petrel undertakes a needle-in-a-haystack search to find all four ships.

Rob Kraft is hunting for Musashi, the biggest battleship ever built and considered unsinkable by the Japanese. How did the U.S. Navy sink this "indestructible" ship? And why did it end up in 10,000 pieces on the sea floor?

Research vessel Petrel picks up what they believe to be the debris trail of the USS Johnston.