The Hardy boys end up on the salvage ship that is sent to search the "Katawa", which happens to be sunk very close to Whalebone Island. While they are on board, they notice another salvage ship in the area as well. Once the diver is lowered to the sunken ship, he finds that someone else has already been there and stolen some of the ship’s equipment. On a later dive, the diver is nearly killed when a squid triggers a booby trap that was intended for him.