Brad Ludden, 31, is an expedition kayaker. Use his tips to keep your head above water.

“There’s a calculated risk to what I do because I can never fully predict a river – and injuries are part of that equation. I’ve broken ribs, dislocated a shoulder and even have a waterfall named after me, ‘the Nosebreaker.’ But my most expedition-threatening injury happened on dry land. I was scouting a rapid in Laos when I slipped on a muddy rock and cut my hand to the bone. I didn’t have sutures, and it took a day to find a doctor who could sew up my hand, sans anesthetic. I still have a nasty scar. What I learned: (1) Put on gripping footwear, a life jacket and a helmet before stepping into a kayak; (2) make sure your first-aid kit is stocked before you start a trip.”

Major rapids aren’t the only danger you’ll encounter in kayaking
In a kayak, you’re the captain, the crew, and, if things go bad, the corpse. “I love kayaking,” says Dr. Travis Stork. “It’s also a sport that inspires fear in me. If you don’t fear going into the river, you probably shouldn’t be kayaking.” Why? Because there’s no telling what lies beneath. “If you see a downed tree, assume there’s a ‘strainer’ under the surface – limbs that create a damlike effect,” says Stork. “Like a colander, the limbs catch all the debris that comes downriver while the water keeps flowing.” Strainers can increase the force of the current, potentially trapping you against the limbs or even pulling you under. If you see a fallen tree or branches poking out of the water, paddle to the opposite side of the river to avoid becoming just one more piece of debris.

Potentially even more treacherous are hydraulics, where water spills over a big rock and curls back upstream. The vortex is most powerful at the surface, so the best way to escape is to submerge the bow of your kayak (or dive down if you ditched it), says Stork. That way the downstream current beneath it can ferry you out. Forced to jump ship? Replicate a vessel by floating on your back with your head up and toes forwards, skimming the surface, to avoid rocks.