Spain's Felipe Perrone Rocha, left, puts his hand on United States' Tony Azevedo while defending during a men's semifinal fifth to eighth place water polo match at the 2012 Summer Olympics, Aug. 10, 2012.
The caps, which tie under the chin, may look like something your great-grandmother may have donned at the beach, but they have a practical purpose beyond making your teammates easily recognizable. They are intended to protect players from popping their ear drums. A wet ball hitting an ear can create suction or a vacuum that can damage the inner ear. Even horsing around in a friendly game, you’ll want these plastic domes inset into the caps ($15) to protect your the ear from any blows.