As you are rubbing your hands in expectation, the director of Poseidon, sympathetic to your 8 bucks, glosses over any unnecassary character development and jumps straight to the action within 15 minutes of the start of the movie. Without any detail being supplied, the hapless audience is told that the Poseidon has been struck by a 150 ft. rogue wave and the ship has turned upside down (as if the passengers, now standing on the cealing are dumb enough to not figure this out). The film is not helped by its irritatingly banal dialogues. At the time when the grand central ball room is looking like the mangled remains of Hiroshima after the bombing, replete with disfigured corpses flying around every which way, one person asks the other, "How bad is it". "Really bad". As this line basically sums up the movie you can only tear apart those last remaining hair.
As the most foolish captain in the history of foolish sea-disaster movies cries to maintain status-quo as he thinks that help will arrive shortly, it is no surprise when a group of dare-doers led by the affectedly unnerved Lucas decide to reach the hull of the ship and get out. From this point you can basically guess whats going to happen in the movie. The group consists of Lucas (the daredevil hero), a former mayor with his daughter and her boyfriend, a mother with her child, a mexican waiter, a latino and a suicidal gay businessman. As far as final survivors are concerned, you make the following conclusions:
1. The mother and the child are not going to die as possession of a child imparts an immortalty to the mother and it is too sickening to kill a child, no matter howsoever irritating and troublesome he might be.
2. Josh Lucas is not going to die as he is ofcourse the "Hero".
3. Either of the girl or his boyfriend might die but if she has an expendable father, both might get saved.
4. Since the mexican waiter and the latino are played by relatively unknown characters, they will be the first to die.
and the movie lives up to all these observations. The only other things which should have been un-guessable are well, guessable. Like the lift falling down when the last guy just makes out of the vent. The sudden movement by an assumed deadbody accompanied by an orchestral bang. The water drowing the hero for just as long as he might survive.
The sole revelation of the movie was that the actors, instead of being homo-sapiens, belonged to some kind of a human-fish breed who could hold their breaths for unimaginably long intervals of time and traverse unimaginably long distances under water.
A final word. You can put your time to better use by counting the number of grass strands in your lawn.