Newly engaged couple, Jenna and Tyler celebrate their engagement at a tropical resort along with the fiancé’s young niece Tori and his aunt Mel. They enjoy lounging by the pool while Tyler and Tori seek out more of an adventure and book the group on a snorkeling tour with a local outfit around the island. Jenna is hesitant of the excursion at first, due to her deep fear of the ocean and the creatures below but Tyler ends up convincing her to join. Soon they all board the boat and set out to the open water lead by their charming and overly friendly guide Jones. Tensions rise between Jenna and Tori as the young niece continues to mock her aunt of her underwater fears but ends up convincing her to dive with the harmless whale sharks. Jenna returns to the boat to find Tyler missing and sets out in the water to find him but is soon surrounded by great white sharks summoned to the water by Jones and his crew by dumping dead fish in the water. Jenna and Tori are immediately forced to put their differences aside to team up and defeat the enemies above and below the surface.