Beach bonding session! Leaving their husbands and kids behind for a weekend, Reese Witherspoon and Drew Barrymore enjoyed the ultimate girls-only getaway with pal Cameron Diaz in Tulum, Mexico, where they hit the surf for a little fun in the sun.

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Witherspoon, 36 -- who welcomed her third child, son Tennessee, on Sept. 27 -- showed off her post-baby body in a modest, red-and-navy striped halter-style one-piece. Fellow new mom Barrymore, meanwhile, tested the waters in a black-and-white polka-dot bikini with retro high-waisted bottoms and a bandeau-style top.

"Reese and Drew have bonded over their babies and losing the baby weight," a source told Us Weekly of the A-list actresses, who gave birth within 24 hours of each other last fall. (Barrymore, 38, welcomed daughter Olive, her first child with husband Will Kopelman, on Sept. 26.)

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The ladies were joined on the beach by Barrymore's BFF and Charlie's Angels costar Diaz, 40, who showed off her famously fit physique in a skimpy two-piece with yellow bottoms and a striped top. "She seemed excited to just be with her friends and be in a healthy, fit place where she could work out all day and relax," an eyewitness told Us of the What to Expect When You're Expecting star.

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Indeed, the trip was a productive one for the trio, who did yoga, ran on the beach, swam, and noshed on healthy meals for five days. "They all hung out together and seemed to be good friends," a source said of the group. "All the girls were very social and had a great bonding experience."

This article originally appeared on Reese Witherspoon, Drew Barrymore and Cameron Diaz Bond During Mexican Beach Getaway: Pictures