There really is a first time for everything. The usually stone-faced Ashley Olsen was photographed not only smiling — but she was also in a bikini! Clad in a cute red-and-yellow striped top and solid black bottom, the billionaire fashion mogul splashed around in the waves in Maui, Hawaii, last week during a getaway with friends, including her twin sister Mary-Kate … who remained bundled up on the sand in a polka-dot dress, light blue cardigan, hat, and sunglasses.

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Baring it all in a bikini is a bold move for Ashley, who usually stays covered up, as does her sister, whose fashion sense has often been compared to a bag lady due to the many loose layers she typically wears. In the past, the 25-year-old former "Full House" child stars have been picked apart for their super-skinny frames and have even been the subject of anorexia rumors, especially MK, who sought treatment for the disease just after her 18th birthday in June 2004. But based on these new pics, Ashley may be thin, but she seems to be far from unhealthy.

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While Mary-Kate has continued to act here and there since they last starred together as teens in "New York Minute," Ashley has kept herself busy with her many fashion ventures, including the sisters' extremely successful clothing lines, The Row and Elizabeth and James (the latter is named after their other siblings). "We worked non-stop until we were 18," Ashley told Elle UK last month. "I wanted to work on other things. It doesn't mean I'm not interested in Hollywood; I like the way it operates and the people who are involved and the sense of possibility. But if I ever do get back in, it's not going to be as an actress."

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