The weather is getting warmer, even hotter in some national parks, and while rivers are alluring for their ability to cool you off, they also can quickly kill you. In Yosemite National Park, rangers have been working on their swift water rescue techniques to save your life, but the best measure of safety is to stay out of the water, as this video explains.

According to park staff, water-related fatalities are the leading cause of accidental deaths in Yosemite and the National Park Service as a whole. Yosemite had four drownings in 2016 and several more near-drownings. 

Moose Mutlow, a swift water rescue coordinator, says that two-thirds of the search-and-rescue missions he's been on in Yosemite over the past ten years have resulted in fatalities.