Shirtless

Summer typically means a lot of time spent outdoors, and there's no one who knows more about what's it like to work up a sweat in the sun than athletes. To celebrate the official start of Summer at the end of this week, we're looking at a few of the best beach and pool moments from our favorite sports stars — you don't have to be an avid sports fan to like these celebrities! Click through to see Serena Williams, David Beckham, Ryan Lochte, and more athletes let loose when they're not working on their game.

Mariah Carey wore two different tiny swimsuits while filming in Southern Italy with fellow recording artist Miguel yesterday. The pop icon showed off her fit physique when she shared a photo collage of herself in a black cutout monokini on Twitter with the caption, "Behind the scenes on set with @MiguelUnlimited!! Coming soon." As part of the shoot, Mariah and Miguel went swimming in the blue grotto, off the island of Capri, and hopped on a yacht after climbing out of the water. The duo have been spending time together since collaborating on the song "Beautiful," which was released last month and is a track off Mariah's highly anticipated 13th studio album. The album, the official title of which has yet to be released, will drop July 23.

Much of the hype may be due to Mariah's frequent Facebook, Twitter, and Instagram teases. While she announced the album release date on her personal accounts, Mariah also took to Instagram yesterday to share a personal snap of herself in blue waters with the caption: "A much needed splash after hours pon de mic singing for my beautiful lambily." In the post, she was addressing her fan base and revealed that her new work encompasses "three years of my soul." Mariah has returned to song-making after announcing last month that she will be not be returning for the next season of Fox's American Idol.

Harry Styles fit in serious shirtless time while in Miami recently. He stripped down to a pair of white shorts to hop on board a yacht with his One Direction bandmates in Florida on Saturday and also showed off his abs last week during a night out with his pal Niall Horan. Harry and Niall went shirtless after the sun went down, and the duo stopped to take pictures and greet fans as they departed their boat. The One Direction crew fit in fun in the sun between taking the stage in Ft. Lauderdale and Miami last week, though they've since moved onto Nashville where they are schedule to perform tomorrow.

While Harry's been showing skin in Miami, he chose a much more formal look for a special occasion earlier this month. Harry buttoned up in a tuxedo to serve as the best man at his mom Anne Cox's wedding in Cheshire, England, two weeks ago, joining the long list of celebrities taking part in wedding season.

Tom Cruise went shirtless for his Father's Day celebrations in Malibu, where he joined his son, Connor Cruise, for a stand-up paddleboarding session. Tom wasn't the only famous dad to spend the day with his son — see how all the other stars celebrated Father's Day.

Tom's latest outing with Connor comes after they joined the Beckham family in the stands at an LA Kings playoff game late last month. Tom may have more time on his hands to dedicate to his kids since he recently dropped out of Warner Bro.'s Man From U.N.C.L.E., which is to be directed by Guy Ritchie. Man of Steel star Henry Cavill is reportedly in the running to replace him in the classic spy series film.

We're used to seeing plenty of shirtless Stephen Amell on the hit show Arrow, but we got an extra bonus on Thursday when his wife, Cassandra Jean, showed skin as well. The two were seen lounging by a pool in Monaco, where Cassandra displayed a little more than just her bikini body — she revealed her baby bump! Stephen and Cassandra revealed their pregnancy news earlier this month, and she first showed off her stomach on the red carpet at the Monte Carlo TV Festival over the weekend. It's the latest in a string of exciting news for the duo, who celebrated their marriage for a second time in May after first tying the knot in a private ceremony last December. They also have the second season of Stephen's Arrow to look forward to after it was renewed by The CW earlier this year.

Princess Beatrice and her boyfriend, Dave Clark, hopped on a yacht off the coast of Antibes, France, with a group of friends on Friday. The lavish getaway may be turning into a tradition for the couple since they took a similar getaway together this time last year. After boarding the large vessel, Dave and Beatrice wasted no time getting into vacation mode. Dave stripped off his shirt to ride a Jet Ski and jump on a trampoline in the water, and he even showed off his skills by diving off the side of the boat. He later met up with Beatrice, who wore a black bikini, for a dip in the hot tub.

The fun continued on Saturday, when Dave and Beatrice met up with Ashton Kutcher and Mila Kunis for a visit to Saint Tropez. The group took a small boat to the shore, where they stopped at Club 55. On Sunday, they got together again for a trip to dry land after Ashton went shirtless on the deck of the yacht. Dave, Beatrice, Ashton, and Mila have already spent time together overseas since they went on a double date in London last month. Ashton and Mila are stationed in the UK while Mila films Jupiter Ascending with Channing Tatum, but they got away from England for the weekend.

Colin Farrell kept cool by going shirtless after a sweaty yoga workout in LA with a female friend yesterday. His many tattoos were on display as he walked alongside his pal, and the two laughed while holding onto their yoga mats. Colin is back in LA after wrapping up two big movies. He recently finished filming Miss Julie in his native Ireland alongside Jessica Chastain and kept busy earlier in the year by working on Winter's Tale in NYC. Colin has also been hard at work on the promotional trail for his newest project, Epic, in which he voiced the character of Ronin, but took a break last month to celebrate Memorial Day at Joel Silver's annual bash in Malibu. The party wasn't the only recent fun for Colin, since he also marked his 37th birthday last Friday.

Mad Men's Vincent Kartheiser and his fiancée, Alexis Bledel, hung out on the beach in Hawaii on Wednesday. Alexis flaunted her diamond engagement ring while she lounged in the sand in a black bikini next to a shirtless Vincent. News of the couple's engagement came out in March following the duo's first official red carpet appearance together in October last year. They got together while working on Mad Men, and though Alexis's guest-starring role didn't last, it looks like their relationship has. The hit AMC show is currently in its sixth season, and with four episodes remaining, there are a lot of questions still left to be answered. Check out the conspiracy theories on the mysterious Bob Benson, and take a look at last week's maddest moments to get ready for a new episode on Sunday night!

Bradley Cooper stripped off his shirt when he took a dip in the ocean in Rio today. His shirtless swim occurred the morning after he premiered The Hangover Part III in the Brazilian city alongside his costars Zach Galifianakis and Heather Graham. Bradley must have gotten a tip about the perfect swim conditions from his costars as the entire Hangover cast hit the beach without him yesterday. The gang has been on a whirlwind trip around the globe as they do press for the final installment of the Hangover trilogy. Bradley, Zach, and the rest of the cast premiered the film in the States last week, and they did promotional duties for the flick in Paris over the weekend. French fans went crazy for Bradley Cooper, who made many hearts flutter several years ago when he revealed that he is fluent in French.

Olivia Wilde and Jason Sudeikis got away to Hawaii over the Memorial Day weekend. On Tuesday, the couple took a dip in the ocean and kissed amongst the waves. Over the weekend, the couple soaked up the sun on the sand and in the water. Olivia, who wore a purple striped bikini, showed off her paddleboarding skills, while Jason snorkeled shirtless in Original Penguin swim trunks nearby.

Olivia and Jason headed to warmer weather for the holiday after spending the last few months stationed in NYC. Olivia kicked off May by participating in the annual EIF Revlon Run/Walk For Women and later hit the red carpet with Jason for the Met Gala. They were back in the spotlight a week later when they cuddled up in the front row at a New York Knicks game. Since then, Jason's promoted Epic in between his Saturday Night Live duties. His busy schedule will continue with an appearance at June's Spike Guys Choice Awards and We're the Millers hitting theaters this Summer — check out the We're the Millers trailer now!