ASPEN – A search is underway for a kayaker who got caught in a treacherous section of the Crystal River in western Colorado.

The Aspen Times reports the man, a member of Mountain Rescue Aspen, was kayaking with a friend when he entered a section of the river called the “Meatgrinder” just before sunset Thursday. He was pulled under the water and has not been seen since.

Pitkin County Sheriff Joe DiSalvo says crews recovered the boat Friday afternoon but are still looking for the man, whose name has not been released.

The nonprofit river group American Whitewater describes the “Meatgrinder” as “fast-paced, stout, and full of sieves and undercuts.” That section of the Crystal also is known to have a large amount of wood that gets caught on the rocks.

DiSalvo warned boaters to be very cautious in the area.