Kayakers plunge down waterfalls and navigate through churning rapids

It's amazing how calm, even happy, the kayakers in this 
video look as they make the first descent down Brazil's 
Mambucaba River, which drops more than 4,000 feet 
over 20 miles – half of that in just 6.5 miles.

Discovery News - The video features some hairy moments, like when one paddler gets sucked upside down in fast-moving water and trapped beneath a tree branch. Sometimes, the kayakers have to scamper down sheer, wet cliffs to get around treacherous, impassable waters.

For the most part though, they plunge down waterfalls and navigate through churning rapids with skill and style. They almost make it look easy.

Watch the Video!