At this time of year, the Merced River channels enough water to fill an Olympic-sized swimming pool every 30 seconds. Don't be fooled by areas that look shallow or peaceful—even quiet-looking rivers carry the strength of Yosemite's high-altitude snowmelt and thundering waterfalls. A simple slip can be deadly. Keep yourself and your fellow hikers safe by staying on trails and being aware of your surroundings as you hike near water. | Yosemite National Park