Your Yosemite vacation should be all about having fun in the great outdoors. But remember that Yosemite National Park truly is a wild place, meaning that sometimes visitors who are unprepared and don't heed the posted warning signs can get into trouble. In an average year, Yosemite park rangers conduct around 250 search-and-rescue operations. So, take time out now before your trip to learn about the park's safety hazards. That way, Mother Nature won't catch anyone in your family by surprise during your Yosemite adventures!
Swimming in Yosemite National Park is a popular activity, especially after early summer. Ask at park visitor centers and information stations about safe local swimming spots nearby before you get in the water. Popular swimming holes are found along the Merced River in Yosemite Valley and at Wawona in the southern area of the park, as well as at a few places on the Tuolumne River (except at Hetch Hetchy reservoir, where swimming is prohibited).
Among the most common causes of accidental injuries and occasional deaths in Yosemite are water hazards. Most drownings happen when visitors decide to take a dip above a waterfall, then get caught by powerful currents and swept over the top of the falls. Never swim or go wading upstream from a waterfall, regardless of how calm the waters may seem to be. When swimming in streams and rivers anywhere in the park, avoid areas of rapidly flowing whitewater bouncing over half-hidden rocks.
Keep in mind that Yosemite's streams and rivers may be running too fast and furiously for safe swimming until mid-summer. The valley's Merced River can be dangerous to enter in June, when the waters are still chilly and are at high levels due to snow melting up in the mountains. Even strong swimmers can easily be swept off their feet and pinned down by strong currents, whirlpools and boulders in the icy waters of Sierra Nevada mountain streams and rivers.
Streams and rivers can be hazardous to hikers, too. Always exercise good judgment when deciding whether to make a water crossing on the trail, especially because otherwise gentle streams can become a torrent during the high country's snowmelt during late spring and early summer. Rocks in and around streams are often extremely slippery. Once you start to cross, the water may actually be running deeper than it looked when you were standing on the banks. When in doubt, stay out.