While on the island, Leo and the Amigos discover that a nefarious aquatic salvaging company named SeaDross is searching for an ancient pirate treasure called Erebos.

Leo and his friends race against time to locate the Erebos, diving to several underwater locations including: a sunken Ferry, a crashed 747, an old cruise ship, a pirate Galleon and an ancient underwater city called Telospolis.

Leo eventually ventures to the sunken submarine to recover the Erebos and is successful in returning it to Telospolis, calming the oceans.

The player, Leo, earns money by finding precious materials with their metal, glass, wood, clay, and stone sonars, and looting artifacts from shipwrecks.

This money can be used to buy equipment allowing a player access to deeper and more challenging dives.