MOAB — The first reaction as rafters stare down the throat of the oncoming rapid in Cataract Canyon is to unconsciously tighten the grip on whatever it is they happen to have hold of. Next comes a deep breath, a glance back to make sure the person on the oars sees what they see, followed by some doubts as to whether the small rubber raft, about to be swallowed, whole, is big enough to tackle the rising corridor of giant waves.

Carried along by the water and a few strokes of the oars, the boat rolls and pitches, then rises up, almost vertical, then rolls and pitches and falls again ... and again ... and again, all the way to calm water. That's when the anticipation of the next series of white-water rapids sets in.

The uncertainty, the anxiety and the excitement modern-day river rats enjoy must be close to those feelings experienced by John Wesley Powell back in 1869 on his first trip down Cataract, except today's runners have the benefits of Powell's experiences and the flood of river runners who have followed.

Powell had nothing to go by, only the experiences of the rapid he had just floated. He knew nothing of what lay ahead. River runners today know the river as well as they do the route back home.

Also, Powell's boat was wooden, much smaller than today's rubber rafts, and it leaked. He made frequent stops along the Green and eventually the Colorado for repairs and to carve new oars to replace those broken in the rapids. Today's boats are flexible, comfortable and self-bailing.

Experience has also taught guides tricks to rigging a boat to ensure everything stays in place, the bow and stern are clear for passengers and the oarsman has unrestricted movement to maneuver the boat, all intended to handle Cataract's boiling rapids.

Powell would write that the rapids he encountered in Cataract were the most difficult he'd faced.

He wrote: "On starting, we came at once to difficult rapids and falls, that in many places are more abrupt than in any of the canyons through which we have passed, and we decided to name this Cataract Canyon."

It is well known that the rapids in Cataract Canyon can be as powerful and difficult as those in the Grand Canyon, which is considered the grandest of all white-waterrafting trips. There simply aren't as many rapids as on the Grand.

One thing that has made Cataract the preferred river trip is time.

The 120 miles of water from Potash through Cataract Canyon and out at Hite can be floated in from one to five days. To make it through the Grand Canyon on a motor-powered J-rig takes between seven and nine days, and up to three weeks to row the 300-plus miles.

It is this shorter trip, the huge rapids and the natural beauty found along the Colorado River, with sheer red-rock cliffs, stretches of green tamarisk and broken-rock escarpments connecting the cliffs with the river, that has made Cataract Canyon among the most recognized and sought-after river adventure in the world.