By STEPHEN REGENOLD

Just off Interstate Highway 70 in eastern Utah, in the steep topography north of its namesake town, the snaking Green River cuts a deep gorge through a backdrop of desert monoliths and thousand-foot cliffs. My view of this gorge last month on a visit to the area was from a riverboard, soaking wet and half submerged at face level with the whitewater.

The sport of riverboarding — a whitewater niche that involves running rapids on your belly with a buoyant boogie-board-like shell — has garnered a small following in the United States. Colorado, California, West Virginia, and Oregon, notably, have riverboarding scenes; it’s a rising fringe with whitewater aficionados elsewhere.

In Utah, dressed head to toe for the sport in fins, booties, a wetsuit, padding, a life vest, webbed neoprene gloves, and a helmet, I had an absolute blast busting through waves and shooting the swift slots between boulders, ominous and half submerged on a Class III section of the river.

As a competent swimmer and experienced whitewater kayaker, the sport came natural to me; the gear — all top-end equipment supplied by riverboarding retailer www.FaceLevel.com — made the experience all the more epic and fun.

My board, the $435 StreamJet model from Rocky Mountain Riverboards (www.rockymountainriverboards.com) is a polyethylene foam model equipped with a hard plastic shell to protect against rocky rapids. Half your body rests on the board, while legs drag behind to kick and steer. Nylon webbing handles and brace grooves for your elbows provide further control in swift water.

Body armor is de rigueur in this sport, and to protect my knees and shins on the Green River I wore SixSixOne’s 4×4 Knee/Shin Combo guards ($40, www.sixsixone.com), which are bulky mesh, plastic and foam leggings developed for the sport of downhill mountain biking. My gloves, the $15 Pro-Pel Paddle Glove by Henderson (www.hyperflexusa.com), have webbed fingers for extra propulsion and power while swimming.

On the river, my group swan nine miles downstream in about three hours, floating through flat sections in a fast current and dropping into long rapids every half hour or so. I was able to swim and steer with confidence by the third set of rapids. The StreamJet board — buoyant, strong and easily maneuverable — bolstered my confidence as the whitewater exploded all around.

Leg padding, I discovered, is essential. Near the end of the float, at the top of a frothy drop, my board schussed into a deep channel between boulders that hid a spike of submerged stone that unluckily made abrupt acquaintance with my right knee. Without the SixSixOne padding of thick foam and hard plastic the impact would have been traumatic.

But despite the scare, I was hooked after just one run downstream. Riverboarding is a must-try new game for any adventure junkie, in my humble opinion. Just be sure to bring the right gear.