Benjamin "Finn" Finnegan (Matthew McConaughey) is a treasure hunter looking for 40 chests of treasure known as the "Queen's Dowry", that was lost at sea with the 1715 Treasure Fleet. In his search to find the treasure, his marriage to Tess (Kate Hudson) falls apart. Tess has been working as a steward on a huge yacht owned by multi-millionaire Nigel Honeycutt (Donald Sutherland). Finn finds a clue to the location of the treasure and manages to get on Honeycutt's yacht ("The Precious Gem") and convince him, his daughter Gemma (Alexis Dziena) and Tess to join him in searching for the treasure. A local gangster named Bigg Bunny (Kevin Hart) and Finn's mentor Moe Fitch (Ray Winstone) are intent on finding the treasure first.
The Precious Gem and Moe's vessel compete to find the treasure in The Bahamas. As Finn attempts to secretly take down Moe's search grid, Finn discovers a sword which is a clue to finding the treasure. Finn and Tess follow the clues to an ancient church and discover a grave containing a diary describing the location of the treasure. Bigg Bunny and his associates, who have been following Finn and Tess, take Tess hostage and assume (incorrectly) that Finn was killed. Bigg Bunny forces Tess to aid him in the search for the treasure in a blowhole, the location revealed in the diary. Tess finds the treasure in a cave beneath the blowhole. Meanwhile, Finn and the Honeycutt enlist the help of Moe in taking the treasure out of Bigg Bunny's hands. They arrive as Bigg Bunny sends one of his associates to bring him the treasure, and the other to take out Moe as he swim towards Bigg Bunny's floatplane. The blowhole kills Bigg Bunny's employee and traps Tess and Finn, while Moe tries to stop Bigg Bunny from taking off. Finn saves Tess only to have Bigg Bunny kidnap her from him again. Gemma gets Finn to Bigg Bunny's plane on her personal water craft and Finn leaps on the planes pontoon as the plane takes off. As Bigg Bunny attempts to shoot Finn, Tess kicks Bigg Bunny out of the plane and sends him into the ocean. The final Bigg Bunny employee, is taken prisoner by Moe (after he has shot Moe in the leg with a speargun).
Finn and Tess are reunited and save the treasure together. Finn, Tess, Nigel, Gemma, Moe and those who contributed in helping or finding the treasure open a museum displaying all of their finds.