Catch a wave," the Beach Boys sang, "and you're sitting on top of the world."

I won't be telling you about the top of the world.

If, however, you want to hear about the world's depths - how the churn of the sea makes your limbs flail in entirely new directions, how the ocean bottom feels on your forehead, how tiny sea-shell shards get along with bare knees - I'm your man.

When, at the beach, your 14-year-old son says he wants to take a surfing lesson, you could just fork over the dough and drop him off, experiencing the thrill of surfing vicariously - free of scrapes, rashes, sunburn, sore muscles and exhaustion - as he excitingly recounts it later.

Or you could momentarily abandon your grown-up good judgment, forget about that episode on the skateboard last year, and sign up, too.

For the best thing about surfing - next to the thrilling sense of freedom one allegedly feels while riding on a wave - is that when you fall, you don't land on concrete. And the next best thing to getting up on a wave yourself, or maybe even better, is seeing your son or daughter do it.

Setting up a lesson is easy - assuming you know whom to call, and that he or she, commonly being laid-back sorts, gets back to you. Surfing instructors aren't usually listed in phone books, but the folks at most surf shops, if they don't offer lessons, can refer you to one.

Some instructors, like Brett Buchler, who runs Surf Sessions in Fenwick Island, Del., are schoolteachers who spend their summer months tutoring vacationers and residents in the art of surfing.

Setting up a lesson with Buchler took one phone call - show up at his place at 7 a.m., he said, and he would take it from there.

About a half-dozen novices did, most piling into Buchler's well-worn van for the trip to that day's location - the site can vary daily - in Ocean City at the end of 36th Street.

Buchler, a 52-year-old teacher of seventh-grade geography, sized us up and handed us wetsuits before we hit the beach.

My son slipped right into his. I pressed, squeezed, squirmed and otherwise loaded myself into mine, waddling down to the beach feeling like the Michelin Tire Man. Buchler, noting it was so tight as to restrict my movement, not to mention my breathing, handed me a slightly larger one, and I suited up again.

By then, the other students were practicing on the sand - drawing lines and lying atop them; then, as Buchler instructed, rising so that their feet landed on the line, all in one quick and fluid movement.

That is something I - being a different kind of 52 than Buchler - would normally do with a few pauses and grunts. Some recent back problems made the prospect seem even more unlikely.

But I tried it his way. It was neither quick nor fluid, but it was close enough that Buchler didn't send me packing.

"Sometimes I send people home to do push ups," Buchler, sunglasses perched atop his gray hair, said.

He ran through some basic tips - most dealing with safety - and advised us on how to get beyond the breakers, which can be the most strenuous part of surfing and is no time to be tentative.

"You have to fight to get out there sometimes," he said. "You have to be aggressive because that ocean is aggressive."

Carry the surfboard at your side on the way out, he warned, holding it over the waves. If you hold it in front of you, and a breaking wave hits it, "you will go down; it will knock you over."