Jessica Alba Jessica Alba

In Honey, she danced until she couldn't dance no more. In Sin City, her stripper did wonderful things with a lasso and chaps. In Fantastic Four, she was out of sight as Invisible Woman Susan Storm. And now, in the thriller Into the Blue (in theaters Sept. 30), Jessica Alba once again has put her mettle to the metal, playing the self-sufficient lady love of a treasure hunter (The Fast and the Furious' Paul Walker) who unwittingly digs up big trouble on the Caribbean seafloor.

So, considering all the above, when is Alba going to give herself (and her body) a breather? "I'm with you on that!" she tells TVGuide.com, laughing. "I actually thought, in my really delusional mind, that I was going to get paid to hang out in the Bahamas and scuba dive for four months. 'Hmm, that's not a bad job.' And then I realized we'd be shooting in the winter, with wild sharks in every single scene that's in the water."

The actress also got a surprise from her Into the Blue wardrobe (and in a way that will undoubtedly delight many male theatergoers). "I thought we'd be wearing wet suits — because if we were real divers, we'd have on wet suits — but they were like, 'It's the summer.' I said, 'Is it summer in the movie? Because right now, it's cold!'"

But even with the less-than-balmy temps and the less-than-practical bikinis, Alba enthusiastically dove into her role and the many underwater and action scenes. "The essence of the movie, and the reason I wanted to do it, is that it's a real page-turner," she tells us. "I read the script in 45 minutes and was on the edge of my seat the entire time. Plus, I knew it was going to be gorgeous."

Having starred on the mid-'90s version of TV's Flipper, Alba was no stranger to scuba diving or communing with aquatic life — although she admits she is more used to dolphins than to their angry, sharp-toothed ocean mates. "Sharks are pretty terrifying animals, because they're not very bright and they're pretty much blind, so they don't see the difference between you and a fish. So the [Jaws] theme song is in your head the whole time," she says. "Paul was fearless, he didn't mind them, but I was like, 'I need my fingers! I don't want them to bite me!'"

Her Into the Blue heroine, however, is made of tougher stuff — a quality Alba sought to emphasize by amping up an otherwise typical "guy saves the girl" scenario. Recalling a sequence that would have left her character MIA for much of the third act, she says, "I said to [director] John [Stockwell] and the writer, Matt [Johnson], "I think I'm probably the most experienced person here in doing action, soooo... what if I talk to the stunt coordinator and figure out something for me to do? I mean, girls get rescued at the end of the movie all the time. So I literally came up with the action sequence with the stunt guy. Before, I was just waiting for Paul to come save me."

Alba can't help but acknowledge that many of her recent roles have demanded she be in picture-perfect shape and, in some cases, play up that fine form in promotional materials. "I don't think I play 'super-hot chicks'; I think I play people who happen to be in bathing suits," she explains. "For some reason, everyone sort of emphasizes me being 'the sexy one,' but in this I'm the sweet girl next door!"

Then, getting back to our original point, she says that her next project, the independent film Awake (in which she costars with Hayden Christensen), will offer a most welcome relief from butt-kicking duty. "I have not had as many opportunities to do the kind of acting that I have wanted to do and that I am trained to do," she points out. "That's why I'm doing Awake, which is character driven. I don't have to wear a bathing suit or chaps or a superhero outfit. And hopefully people can see that I'm not just somebody who sells movies."