Skimboarding involves riding a flat, thin, finless, shortboard-looking thing. It is usually made from high density foam surrounded by carbon fiber or fiberglass and is about 3-4ft long. The rider throws the skimboard on the wet surface of a retreating wave and then jumping on it. The skimboarder then rides the thin layer of water on top of the sand into the deeper water and into the face of the breaking wave, usually ending the ride on a closeout shorebreak.
This creature can be seen pacing back and forth on the shore waiting for the right wave to roll in. They get more rides when the beach has a steep dropoff. That way the wet sand leads up to a bigger breaking wave. Otherwise they just ride wet sand into whitewash. Laguna Beach seems to be their primary breeding ground.
Not sure what the advantage is here, but to each his own. Perhaps some people who are shark spooked would prefer this as you don't have to venture off into deep water. Under the right conditions these riders can get some nice waves. Frankly, I don't see many rides most of the time around San Francisco Bay Area. Usually these riders are really young and limber. I knew somebody from Long Beach State (Santa Cruz native) that really liked it. Apparently pics of him made the local skimboarding publication.
Skimonline.com video of skimboarders in southern California....good skimboarders on good skimboard waves