En route from New York City to Greece on New Year's Eve, majestic passenger ship the S.S. Poseidon is overtaken by a tidal wave. With the captain (Leslie Nielsen) dead, surviving passengers, including the passionate Rev. Scott (Gene Hackman), band together in the ship's ballroom. The group struggles to avert fires, flooding, structural instability and mechanical malfunctions as they make their way through a maze of ladders and tunnels in their desperate attempt to escape a watery grave.