The 34-year-old athlete, who announced last week that she was withdrawing from the WTA Finals and the China Open and taking the rest of the year off to recover from injuries, posted a photo of the trio tubing on the San Marco river in Texas on her Instagram Sunday.
She captioned the snap, “Core memories with @valgabond @coltonlhaynes love you guys.”
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Despite the recent upset – which ended her bid for a historic Grand Slam – Williams appeared cheerful during the fun outing, showing off her famous figure in a high-cut, printed red bathing suit.
Haynes, 27, posted the same photo on his Instagram account with the caption, “Cheers to more core memories wit these 2 @serenawilliams @valgabond 🙂 What an epic adventure.”