River of Diamonds [1990] [DVD]

Mining engineer John Tregard (Rambo) travels to an island off the coast of West Africa where the reefs are encrusted with precious stones. It's said that Mercury Island is cursed, for all who dare go there die.

An elderly adventurer named Shelbourne (Mayne) is determined to keep Tregard from locating the island's underground diamond stream. In his search for treasure, Tregard encounters deadly snakes, rotting corpses and more!