The sun wasn't the only thing burning up the beaches in St. Barts this week! Jessica Alba's smokin' bikini body also generated some serious heat, as she and husband Cash Warren enjoyed a little tropical vacation with friends.

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On Thursday, April 4, the 31-year-old Sin City actress -- mom to daughters Honor, 4, and Haven, 19 months -- showed off her flawless, super-fit physique in a sky-blue bikini top with bright-orange bottoms. She appeared to be in great spirits all afternoon and was spotted laughing and playing around in the clear water.

At one point in the day, the sexy star took a break from the surf to catch a few rays on a jetty in the middle of the ocean. Stretching her long, toned legs behind her, she gazed happily out at sea as small waves crashed around her.

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The eco-friendly entrepreneur -- she started a healthy-living business called The Honest Company -- also spent some quality time on the beach with her husband, whom she met in 2004 and married in L.A. four years later. They were joined on the retreat by Alba's pal Nicole Richie, a mom of two herself (to daughter Harlow, 4, and son Sparrow, 3). Richie showed off her own incredible bikini body in a bold, teal two-piece.

Alba was clearly enjoying herself on the group getaway, but she's not all play and no work. As she told Lucky in August 2011, just a few weeks before giving birth to daughter Haven, those enviable curves don't come easy. "I have a hard time with portion control, so I have 1,200-calorie meals delivered," she told the mag. "But I also work out, so basically I'm starving. It sucks."

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She also recently confessed to Women's Health magazine that she "hates" exercising, especially when it feels like exercising. "I like doing dance classes. That’s fun. Like hip hop class, mixed with like core pilates-type exercises. And sometimes I do sprint intervals just because I hate working out," she said. "Anything where I have to do something but I can get my mind off of doing it, that's so much better for me than anything that's repetitive. Or the music has to be loud and I have to be moving."

This article originally appeared on Jessica Alba Flaunts Sexy Bikini Body on Vacation With Nicole Richie, Cash Warren in St. Barts