A former smuggler who works as a shark wrangler.
- Action Hero: Nautical version.
- Book Dumb: Describes himself as "poor dumb Carter," but clearly knows his stuff when it comes to being underwater, and specifically dealing with sharks. Also skilled with improvised explosives.
- Dark and Troubled Past: He was a smuggler, currently on parole.
- Great White Hunter: Gives off the vibe as the facilities shark wrangler, obtaining wild sharks for the experimental sharks to eat, tranquilizing them for tests, and recapturing them when they escape.
- The Hero: Downplayed. Definitely the film's male lead, comes up with the plan to kill the last shark, but Preacher is the one to actually execute it. Notably, Carter kills none of the sharks himself.
- Ignored Expert: He tries to convince Susan that bringing in the sharks ahead of schedule is a terrifically bad idea.
- Nerves of Steel: Is the only one who willingly goes into the water with the sharks repeatedly, lacking the primal fear others have for them.
- Not So Stoic: Has a dry, wry sense of humor, but nothing much gets to him. Until Susan reveals exactly what's going on, at which point he gets pissed.
- Take My Hand: To Janice when he's dangling over her by a ladder. They can't quite reach.
- Unresolved Sexual Tension: With Susan. And boy does it stay unresolved...
- What the Hell, Hero?: He gives a much-deserved one to Susan.Carter: How much dynamite do you have to set off in your ears before your head clears?Susan: You wouldn't understand.Carter: I wouldn't, huh? Dumb old Carter wouldn't understand that you used us? That you used me? Someone on the water who wouldn't make waves. Someone who wouldn't ask too many questions...because he had something to lose.Susan: You don't see what we've done here.Carter: No, what you've done is taken God's oldest killing machine and given it will and desire. What you've done is knocked us all the way to the bottom of the goddamn food chain. It's not a great leap forward in my book.Susan: The people we'll save....Carter: Jim? Brenda? Us?
Dr. Susan McAlester
The head scientist in charge at Aquatica.
- All for Nothing: Not happy that all her hard work was ruined.
- The Caretaker: She took care of her Alzheimer's-afflicted and beloved father.
- For Science!: Averted; Susan's desperation to find the cure for Alzheimer's stems from personal reasons, not scientific altruism.
- Half the Man He Used to Be: The final shark rips her in half before devouring her remains.
- Hot Scientist: Very much so.
- It's All About Me: While her reasons are justified and reasonable, there's no denying that it's really selfish.
- Ms. Fanservice: One of the funniest examples ever, where she strips down to her bra and panties to use her wetsuit to protect her from electroshock. Also obtained the only wetsuit in the film to zip in the front, allowing her show some cleavage.
- Not That Kind of Doctor: She says this almost word-for-word when trying to save Jim Whitlock.
- Stupid Sacrifice: Instead of just cutting her hand and dripping blood in the water to attract the shark (which would work in real life owing to sharks Super Senses ) she cuts her hand and jumps in from a point where there was no guaranteed way of getting back out. On the other hand, after having her works reduced All for Nothing and in grief with it, there is a possibility that she just wanted to end her life at that moment.
- Unresolved Sexual Tension: With Carter.
- Well-Intentioned Extremist: She illegally experimented on the sharks, she rushed the experiment and ignored all the tell-tale signs that something bad was about to happen, so she could cure alzheimer's.
- Not-So-Well-Intentioned Extremist: That being said, the others don't agree that it was all worth it, and it's noted that she did it out of selfishness rather than altruism.
- Black Dude Dies First: Subverted; he's the fifth to die behind two helicopter pilots, Brenda and Jim Whitlock.
- Dark Secret: The exact nature of his 'heroic' survival of an avalanche eventually comes to light. The pressure of the situation got to him and his fellow survivors; they turned on each other.
- Eaten Alive: By one of the sharks in the middle of his Rousing Speech.
- Famous Last Words:"We're going to pull together and we're gonna find a way to get outta here! First, we're gonna seal off this—!"
- Honest Corporate Executive: Carter has a slight dislike for him and considers him a 'rich suit'; while he's right that Franklin has a few dark secrets, none of those are related to his work and he's generally a Reasonable Authority Figure.
- Killed Mid-Sentence: The Gen-1 leaps out of the water and snatches him right in the middle of his Rousing Speech.
- Large Ham: Particularly when he gives his Rousing Speech.
- Rousing Speech: Gives one about pulling together and finding a way out. As he begins to outline a plan for exactly that, he's eaten by one of the sharks.
- Surprisingly Sudden Death: In the middle of his Rousing Speech.
- Too Dumb to Live: Giving his Rousing Speech next to an open pool ''he was warned to step away from.'
- The World's Expert on Getting Killed: Has prior experience with survival situations. Would have come in handy, if he didn't get eaten.
- Deadpan Snarker: Talks back constantly, most often about how yes, he does in fact know how to do his job.
- Half the Man He Used to Be: One of the sharks bites him across the waist, ripping him in half.
- Lovable Coward: The most terrified of the sharks, requiring the most motivation to keep moving.
- Vitriolic Best Buds: With Carter; they toss jabs at each other, but they're still pals.
Dr. Jim Whitlock
- A God Am I: Subtly, but creepily there.Franklin: What in God's creation...?Jim: Oh, not His. Ours.
- Bunny-Ears Lawyer:Janice: That's Dr. Jim Whitlock. He's the most brilliant person here.
Franklin: He's pissing in the wind. How brilliant can he be?
- MayDecember Romance: With Janice, who's half his age.
- The Stoic: He's fairly emotionless and detached.
- There Is No Kill Like Overkill: His arm is ripped off by a massive shark, gets heli-lifted in the middle of a violent storm only to fall into the water. Then one of the sharks grabs his stretcher and rams him headfirst into the glass window of his lab. Finally, unless one of the sharks ate him afterward, he either bled to death, or drown once his oxygen supply to his mask ran out as he's clearly still alive after getting smashed into the glass.
Sherman "Preacher" Dudley
- Bald of Awesome: Shaved head, kills two sharks, prays like a badass.
- Deadpan Snarker: To everyone up to and including God.
- Eye Poke: This is how Preacher survives being grabbed by one of the sharks. The behemoth is dragging him through the water in her huge jaws, and he grabs his cross necklace and starts to stab her with it. She lets him go when he damages her eye.
- Pre-Mortem One-Liner: "You ate my bird."
- Supporting Protagonist: Preacher is separated from the other survivors for much of the film, having his own little journey and an encounter with one of the sharks.
- Took a Level in Badass: Kills two sharks while giving a righteous middle finger to Black Dude Dies First.
- You Have Got to Be Kidding Me!: When he realizes he just might die in his own oven.