If you're watching swimming in the Olympics, you might notice a swimmer take off their cap just to reveal *gasp* another cap!
You might be asking yourself, "Why do they wear two caps?" It's a completely logical question to ask, and we've done the homework to help answer it for you. The practice is known as "double capping" and it is quite common.
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Olympic medalist Gary Hall Sr. listed double capping as one of his suggestions to reduce frontal drag, via SwimSwam:
Covering up that thick head of hair and creating a new surface for your head with the reduced friction of silicone is another good way to reduce drag.