What a trio! Taking some time off from the court, Serena Williams spent the past weekend tubing down the San Marco River in Texas with a female friend and Arrow hunk Colton Haynes.

As seen in an Instagram shot Williams shared on Monday, Oct. 5, the 21-time Grand Slam winner, 34, flaunted her curvaceous body in a tangerine-hued, printed one-piece swimsuit, teamed with flat sandals, during the riverside adventure.

Meanwhile, the Arrow alum, 27, who also starred in Teen Wolf's early seasons, worked his ripped physique in a pair of navy-blue board shorts. Williams' media rep, Val Vogt, appeared in the shot, too, clad in a Baywatch-worthy red one-piece. And of course, each one held a tube in hand.

Making sure to shout-out her weekend companions, Williams affectionately wrote, "Core memories with @valgabond @coltonlhaynes love you guys."

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Adding to the cuteness, Haynes re-grammed the shot and added this sweet caption: "Cheers to more core memories wit these 2… What an epic adventure."

While the pairing may seem random, Williams and Haynes appear to be longtime friends, as the actor wished the tennis champ a happy birthday just the week before with a collage of photos featuring their many adventures. With that, he wrote, "On this day, 30fun yrs ago, this beautiful light @serenawilliams was born. What a fun journey it's been 🙂 So happy to have ya in my life & cheers to many more dance rehearsals, karaoke nights, petty squad naps, & spontaneous flights!"

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