context: Benjamin "Finn" Finnegan (Matthew McConaughey) is a treasure hunter looking for a treasure from a Spanish galleon known as the Aurelia, that was lost at sea with the 1715 Treasure Fleet. In his search to find the treasure, his wife, Tess (Kate Hudson), divorces him. 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 BiggBunny (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 diary describing the location of the treasure. BiggBunny and his associates, who have been following Finn and Tess, take Tess hostage and assume (incorrectly) that Finn was killed. BiggBunny 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 Honeycutts enlist the help of Moe in taking the treasure out of BiggBunny's hands. They arrive as BiggBunny sends one of his associates back in to the water to find out who was killed in the blow hole. The blowhole kills BiggBunny's employee and traps Tess and Finn. Finn saves Tess only to have BiggBunny kidnap her from him again. Tess is kidnapped and is completely unconscious. Gemma gets Finn to BiggBunny's plane on her jet ski and Finn leaps on the plane's pontoon as the plane takes off. As BiggBunny attempts to shoot Finn, Tess's eyes start rolling and she wakes up and kicks BiggBunny out of the plane and sends him into the ocean. The final BiggBunny henchman 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 and Tess is shown pregnant. Finn, Tess, Nigel, Gemma, Moe and those who contributed in helping or finding the treasure open a museum displaying all of their finds.
question: Who's jet ski does Finn ride on?
answer: Gemma's