In the film The Poseidon Adventure, what disaster strikes the ocean liner during New Year's Eve celebrations?

In The Poseidon Adventure, a rogue wave capsizes the ocean liner during New Year's Eve celebrations.

The 1972 disaster film begins aboard the fictional SS Poseidon as passengers celebrate New Year's Eve at sea. A massive underwater earthquake generates a tsunami-like wave, which overturns the ship and leaves the surviving passengers trapped inside the inverted hull.

The story follows a small group led by Reverend Scott as they search for a way out. The unusual setting lets the film turn familiar ship spaces—ballrooms, staircases, and engine-room areas—into dangerous vertical obstacles. Its central survival idea is to move toward the ship's upper, now exposed, areas rather than remain in the main dining room.

The movie was adapted from Paul Gallico's 1969 novel The Poseidon Adventure. It is fictional, and the wave is sometimes casually called a tsunami, but the film's immediate disaster is specifically a rogue wave that overturns the vessel.