This dramatic footage shows Canadian Nick Troutman being rolled under the water after miscalculating a drop on a routine practice run.

The 26-year-old was taking part in the 2014 Whitewater Gran Prix which is one of the world's toughest kayaking events. After battling against the rapids and freeing himself from his boat, Troutman was able to swim to the safety of the river bank.

Video (shown below) courtesy of Bear Grylls Adventure