Every spring, something bizarre happens to the water in Yosemite National Park. The water pouring off the falls and flowing through the creeks turns into "frazil ice"—a weird, slush-like substance that's neither pure snow, water, or ice. Even stranger, it behaves and flows like lava, clogging river bends, demolishing bridges, and even grabbing a spectator or two who mistake a slower flow for solid snow.
Yosemite Nature Notes (an amazing in-house video podcast series) captured this once-a-year event on video. It's long, but well worth it:
Anybody else getting thirsty? I have an intense urge for an Icee in my favorite flavor—plain!
via Adventure Life