If you're headed to a lake or ocean this summer for boating and swimming fun, or if you're lucky enough to live near the water all year round, there's a concern that's bigger now than ever before: Recreational Water Illness (RWI). Caused by bacteria and other microscopic organisms in the water of lakes, oceans, pools, and hot tubs, the usual symptoms of RWI are diarrhea, rashes, and swimmer's ear (although it can exhibit in other ways).

Even chlorinated pools can harbor microorganisms for several days before they die, so everybody is at risk of RWI if they spend any time in the water. The good news? RWI is fairly easy to prevent by simply never swallowing water, by drying your ears out immediately after you get out, and by taking a quick shower before and after swimming.