A swimmer putting on a bathing cap.
bathing cap definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a tightfitting cap of rubber, plastic, etc. worn to keep the hair from getting wet in swimming
bathing cap definition by American Heritage Dictionary
A snug elastic cap worn in the water especially to keep the hair dry.