Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is a low-budget predictable but watchable Nicolas Cage action movie. Uncharacteristically, Cage is not the most crazed and unhinged character in the movie. That would be Kevin Durand, who plays Loffler, a U.S. government assassin and super-soldier who has been arrested and locked up on a cargo ship where he is guarded by a group of armed men. Cage is Frank Walsh, an animal poacher with a collection of exotic animals he plans to sell after the ship docks. His Brazilian wildlife cargo includes a Tapir, monkeys, a large white jaguar that is worth a fortune, and several venomous snakes. When we see the snakes in a wire cage (a ridiculous way to keep snakes) it's like seeing a gun in the first act. You know there will be snake action later on, and there is.
This wouldn't be a movie if Loffler didn't escape, so of course he does. After he gets out of his cage, Walsh checks on his animals then radios back to the others: "Loffler let most of the animals out. He took two snakes. If he lets them loose, they'll find the hottest most humid place. You tell Jerome, don't go anywhere near the snakes. They're venomous as hell." A Navy doctor on board, Dr. Taylor (Famke Janssen) asks Walsh if he brought the anti-venom and he responds sarcastically: "Yeah, I would have, Doc, except the pharmacy was closed." Later Walsh tells someone that he put the snakes in a bag (a good way to keep snakes) and Loffler took the bag, which we see him with later.
Loffler picks off the guards one by one, with a little help from one of the snakes. Walsh said that the snakes would find the hottest most humid place, which isn't necessarily wrong, but they would most likely also crawl into some dark place and hide. That's what their long thin legless bodies are designed for. But this wouldn't be a movie if the snakes weren't more of a threat than that, so we see one on the floor of the ship behind some pipes in a room where drinking water is stored. Loffler drained out all the water to make the crew go there, and released one of the snakes, which, of course, did not crawl into a dark place to hide. Instead, it bites the ship's captain Morales on the lower leg when he gets close to the snake. When Morales is brought to Dr. Taylor for treatment she asks Walsh what kind of snake it is and he tells her it's a Bushmaster. She asks about his chances and he tells her that Morales is a dead man. "Even with the anti-venom he'd only have a 20 percent chance." (It turns out, that was enough of a chance, because he survives and is helicoptered out at the end.)
But Loffler has one more trick up his sleeve. He binds and gags Dr. Taylor and Captain Morales' son, then takes the bag with the remaining snake and dumps it in front of them as a goodbye present. This is a very stupid way to use a venomous snake as a weapon. In a movie the snake will always crawl towards the intended victim and try to bite them. In real life, you have absolutely no way of knowing which direction the snake will crawl and even if it crawls towards the targets, if it will bite. It's a ridiculous movie snake cliché that will never die. And again, most likely the snake will head for the darkest hole to crawl into. But we see the snake slowly crawl towards the captives, intercut with other action, until Walsh heroically comes to save the day, stomping his foot on the snake. (He doesn't even do this right. His foot lands so far from the snake's head that it could have turned around and bitten him.)
The snakes, like all of the other animals on the ship, are not very well-rendered CGI. They look very fake, but that seems to be acceptable these days in a mindless action movie like this one. I miss the old days when if you wanted to use a snake in a movie, you had to use a real one, or at least take some stock footage of a real one and cut it into the movie. You can control the actions of a CGI snake much better, but in this case they could have easily used real snakes since the snakes did nothing out of the ordinary.