The
RMS Poseidon, a
British luxury
ocean liner, is making a
transatlantic crossing from
London To
New York City. Former
New York City Mayor and
firefighter Robert Ramsey is traveling with his daughter Jennifer and her boyfriend Christian Sanders to New York, soon to be engaged. Also on board are former Navy submariner-turned-professional gambler Dylan Johns, architect Richard Nelson, Maggie James with her son Conor, stowaway Elena Morales, her boyfriend and waiter Marco Valentine, singer Gloria, and Captain Michael Bradford. As the passengers are celebrating a
New Year's Eve party, officers on the bridge see a huge
rogue wave heading towards the ship. To survive the wave, they try to steer the ship to starboard to take the wave bow-first, but she does not turn fast enough. The wave swamps and
capsizes the ship, killing the bridge officers along with most passengers and crew. In the
ballroom, a badly injured Captain Bradford attempts to restore order and assures the surviving passengers that emergency beacons were launched and rescue is on the way within several hours, persuading them to stay put. Unconvinced, Dylan leads Conor, Maggie, Robert, Richard, and Valentine towards the
bow, where he believes they will have the best chance of escaping the capsized liner. On their way to the bow, they encounter a
lift shaft. When Richard and Valentine are attempting to reach the entertainment section, the bridge they are crossing onto loses balance and falls leading to Valentine hanging from Richard's leg. Dylan urges Richard to kick Valentine off to save his own life; Valentine falls and is killed below. They reunite with Jennifer, Christian, Elena, and gambler Lucky Larry, in the
nightclub, and are the only survivors out of all of the occupants who had been
electrocuted to death by mangled live wires. The group crosses the fallen lift shaft across the flooded lobby, where Larry gets crushed by an
AC chiller. The pressure from the water due to the ship's prolonged submersion causes the ballroom windows to fail, breaking and drowning the occupants, including Captain Bradford and Gloria. With the ship sinking rapidly, the group escapes through a
ventilation shaft and a couple
ballast tanks, although Elena hits her head in an underwater passageway and
drowns. The survivors make their way to a crew lounge, where they find the bow section is flooded and unpassable, until multiple
explosions in the
engine room floods the
stern, lifting it out of the water. They enter the
bow thruster room and are horrified to find the thrusters still running. With their path blocked by the
propellers, and the control room submerged, Robert swims away to turn off the engine. He finds the "shut off" switch to be broken, but presses the reverse button instead, before drowning. With the propellers now spinning in the opposite direction, Dylan throws an
acetylene tank into it, causing an explosion that destroys both of them, and leaving an opening to the outside world for them to escape through. The group jumps out the thruster room and swims to a nearby inflatable raft, just before the ship flips back over, and across the water. The six survivors look on as she sinks stern-first to the bottom of the ocean. After the survivors fire a flare, two helicopters and several ships arrive at the area to rescue them, having tracked the location of the
Poseidons
GPS beacon. ==Cast==