Mystery solved: Why do swimmers wear two caps?

Fourth-Place Medal
Hungary’s <a class="link rapid-noclick-resp" href="/olympics/rio-2016/a/1103927/" data-ylk="slk:Katinka Hosszu">Katinka Hosszu</a>. (AP)
Hungary’s Katinka Hosszu. (AP)

Welcome to Olympic Mysteries Solved, where we answer your most pressing questions from this year’s Rio Olympic Games. Seen something you don’t understand? Drop us a line and we may solve your mystery in a future installment. Today: swim caps!

As you’re watching Katie Ledecky, Michael Phelps and the rest of America’s aquatic Olympians carving through the pool, you might notice that at the end of their races, they peel off one cap only to reveal another beneath. What the heck? What’s going on there? How many caps do they have hidden, one under the other?

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Swimmers wear two caps for two main reasons: stability and speed. (We discussed this very topic four years ago, but it’s cool if you don’t recall.) Many swimmers wear their goggles over one swim cap but under another; the lower swim cap can wrinkle and create drag. The lower cap is generally a latex material, which stays on the head better but wrinkles more, while the upper cap is a silicon material. In a sport where hundredths of a second matter, every tiny bit of drag can be the difference between a medal and a good-job, good-effort. A smooth surface atop the head is thus mandatory.

[Related: A look at Rio’s Olympic venues]

Some swimmers still prefer to go with the single cap. And some, like Dana Vollmer in 2012, lose one along the way. The only rule is, as another famous aquatic talent once said: Just keep swimming.

So now you’re thinking, wait, if two caps on the head are better than one, wouldn’t three be better than two? And four be better than three? Yeah, no. At some point, we start to enter rubber-band-on-watermelon territory, and nobody wants to see that happen.

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Jay Busbee is a writer for Yahoo Sports and the author of EARNHARDT NATION, on sale now at Amazon or wherever books are sold. Contact him at or find him on Twitter or on Facebook.

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