OCEAN CITY, MD. -- For 48 hours recently, southern California seemed only a three-hour drive from downtown Washington. The Pro Beach Volleyball Series detoured from the West Coast to here for the first $20,000 Maryland Open.

For East Coast volleyball fanatics, it was a chance to see the stars of the circuit in action; for vacationers who enjoy the game, the two-man team competition provided an opportunity to see fundamental and strategic volleyball at its exciting best.

A large part of beach volleyball's popularity results from its origin -- southern California. In the late 1940s, surfers, seeking a dry-land activity, who were familiar with the indoor game, began hitting the ball around. They figured that little could be better than emerging from the water and having a relaxing workout.

Although the game has spread, it has remained distinctly southern Californian. Its laid-back nature echoes the lifestyle of the people who invented it.

"In California, there are people in their 60s out there playing," said Sinjin Smith, who has been dubbed "King of the Beach" for his successes on the pro tour. "The California lifestyle is built around the beach, and people all over try to emulate it when they can."

The reason organizers believed big-money volleyball was worthy of being brought east is the popularity the game has taken among beachgoers. This is particularly true of Washington-area residents who flock to beaches in Maryland and Delaware.

For the average beachgoer who seeks a great tan but does not have the patience to lie still for hours getting it, volleyball on the sand is a popular way to soak up the sun and burn off some energy.

A typical pick-up game begins with two or three people knocking the ball over the net to each other. Along comes a straggler here, a group of two or three there. Soon, it's game time. Most of the time, most of the players don't know each other, so nobody cares if a mistake is made. It's just for fun.

The nets that permanently dot the Maryland and Delaware beaches cater to the needs of players at all skill levels. Beach volleyball has a lure that often does not exist in the indoor game. For many vacationers spending large parts of their beach afternoons around the net, this is the only time all year they play.

Volleyball is also the only sport that can be played to its potential on the beach. Frisbee comes to mind, but it requires too much space unless just two people want to throw. Football? It's a space-eater when blankets cover virtually every open area of sand. Volleyball takes up minimal space and allows many to participate.

The social aspects of the sport play a large role as well. A pick-up game is an opportunity to meet people, show-off a tan and check-out the opposite sex. After all, what's a beach for?

Those who play beach volleyball for recreation or social reasons, however, had to take a back seat for at least one weekend to those who play it for paychecks and pride.

On the sand next to the boardwalk here, the crowd of about 1,000 sits around center court. Next to the administration tent, a 20-foot high inflated balloon in the shape of a beer can sways in the wind. In the distance, kids enjoy the boardwalk's 70-foot waterslide. Huey Lewis and the News blares on a stereo.

But when Smith and partner Randy Stoklos begin their second match of the day -- it's still just 10 a.m. -- the music vanishes. They are the No. 1 seeds and, as when Jimmy Connors or Martina Navratilova are on center court, nobody notices the games starting on the peripheral courts.

"It's great the way the players walk through the crowd and talk to the crowds," says one man, wearing sunglasses and white shorts.

"That's just because it's outside," responds his friend, dressed in blue.

"Well, so is a concert, and the musicians don't do that," says the first man, who has been studying the pros."And two things I've noticed. First, when they talk to their partners, they put the ball in front of their faces so the opponents can't see. Also, they always tell each other where to hit the ball."

It's easy to distinguish between the groups of spectators. About two-thirds are knowledgable fans; they talk about the intricacies of the game. The other third are mostly neophytes. Many are quiet; all are fascinated.

"What do you think of this, Joan?" a man, surveying the scene, asks his wife. "It's crazy, isn't it?"

Smith and Stoklos win handily, advancing to the semifinals, and the morning session ends. Everyone gets up from their beach chairs and heads for the water.

Christopher St. John Smith, Sinjin, has won more tournaments and more prize money than any player in the history of Pro Beach Volleyball. A 1979 graduate of UCLA, with a major in economics, Smith is a three-time Pro Beach Volleyball World Champion, in 1979 and 1980 with Karch Kiraly, and in 1982 with Stoklos.

In February, Smith and Stoklos traveled to Brazil and won the world tournament. While many players change partners regularily, they have been together for six years. With only two players trying to cover the 30x60-foot area of a regulation court meant for six, success means teamwork.

Smith is Magic Johnson to Stoklos' Kareem Abdul-Jabbar, yelling directions, making the sets, patrolling the back of the court; Stoklos, all 6 feet 5 of him, controls the net with spikes and blocks.

But the game they dominate varies greatly from its indoor relative. Having the extra ground to cover produces breathtaking dives and lunges.(Landing on the soft sand inspires players to attempt plays they wouldn't even contemplate on a hard surface.)

"Indoor is a much more power- oriented game," Smith says, during a timeout from munching on a chicken salad sandwich. A banana waits to be devoured. "It's also far more specialized. Of the six guys, one or two are setters, and one or two are spikers, and so on. It only requires the player to excel in one or two skills . . . "

A teen-age girl sidles up to Smith. "Could you sign this shirt and hat, please?" she asks, sheepishly.

"Well . . . um . . . O.K," he says, feigning displeasure.

He smiles. She laughs. He signs.

"On the beach, you've got to have all the skills, setting, defense, serving, spiking," said Smith. "You could take a world-class indoor player and put him on the sand and he'd be lost. Very few can make the transition to the beach -- only the guys with all the skills."

Attesting to the dramatic growth in beach volleyball's popularity, Smith points to the immense crowds in California. Many times 20,000-25,000 gather for a tournament, and the Association of Volleyball Players -- the players' union -- is considering building bleachers on certain beaches.

Smith points to the increasing television exposure. This year, ESPN and Prime-Ticket, a southern Californian cable network, will telecast as many as six tournament finals.

But most of all, Smith points to the enormous contributions of Miller Lite, Pro Beach Volleyball's main sponsor. In sponsoring over two-thirds of the 1987 tournaments, Miller Brewing Co. will donate at least $400,000 in prize money, and approximately $800,000 in operational and advertising expenses.

These days, on the beach, Smith, Stoklos and all the top players are swamped by autograph requests; their pro game is hotter than ever.

Meantime, the pick-up game between vacationing beach-goers continues to thrive.

Is it merely a fad? Will the sport's popularity ever dissipate? Not as long as there are beaches.

CAPTION: Volleyball on the sand is a popular sport.

CAPTION: Ryan Sheffer is content with a solid bump pass.