Krakatoa, East of Java

Captain Hanson (Schell) of the Batavia Queen embarks on a perilous search for sunken treasure off the island of Krakatoa. To find a fortune in rare pearls, he must brave a boiling sea, douse an uprising by a horde of convicts, and outwit a greedy crew desperate for more than their fair share - only to confront the most devastating and catastrophic volcanic explosion the modern world has ever felt! (official distributor synopsis)