When they checked into the hotel the case had sent them to, the woman at the counter had informed them about the pool and Sherlock's face had lit up in a way John rarely saw outside the flat. Needless to say, he was surprised.
When they got to the room, Sherlock ducked into the bathroom and burst back out wearing nothing but a snug and flattering black square-leg suit, and John couldn't hide the flush across his cheeks and throat.
"Come, John. Swim with me."
"Sherlock, I didn't bring a suit."
"At least come sit by the pool! Watch me!" He grinned like a child.
Sighing, John followed him, still confused by this turn of events.
But really, of all the surprising talents Sherlock hid, swimming had to be right up near the top of the list. They'd discussed swim meets before, back when they'd been talking about poor Carl Powers, but Sherlock had never mentioned an interest himself. John suspected it had something to do with Sherlock's general disdain for organised sport competition. He didn't stick to any particular lane, any particular style. He just did whatever he felt like doing under the cool blue of the water.
Leaning back in his lounge chair, John smiled and watched Sherlock's lean form cut gracefully through the water in a perfect backstroke.