Amy, her husband James and their baby Sarah travel to Mexico to sail in the yacht of their reckless friend Dan with their common friends Zach and Lauren and celebrate the thirtieth birthday of Zach. They are introduced to Dan's girlfriend Michelle and they drink and recall moments of their past while navigating. Miles away from the shore, Michelle suggest to stop the yacht and swim in the calm water. Amy stays in the boat since she has a childhood trauma with ocean and Dan stays with her. Later, the irresponsible Dan pushes Amy overboard, falling with her in a prank. Once in the water, the group realizes that Dan forgot to put the embarkation ladder and the freeboard makes impossible to climb to the main deck of the yacht. With the baby alone in the boat and stranded in the open sea, they panic and their desperation lead them to a tragic fight for survival.