National Park authorities are on the hunt for a man who may have attempted to go down the Colorado River through the Grand Canyon on a homemade wooden raft.

Thomas L. Robison, 58, of Santa Fe, New Mexico, left his Toyota Tacoma at Lee's Ferry in Glen Canyon National Recreation Area on Sunday.

They think he took his dog, a Welsh Corgi, on the raft and took off down the river.

The Colorado has long stretches of calm water but also has areas of intense whitewater rapids.

Robison is described as white, 5'10" and 160 pounds. He has brown hair and hazel eyes.

His Welsh Corgi is 11 years old and weighs 25 pounds.

Anyone who may have seen him is asked to contact Grand Canyon Dispatch at 928-638-7805.

A missing person investigation is continuing.