The Cabrillo Marine Museum plans a whale of a fiesta.

The Pacific gray whales have forsaken the South Bay coastline after their annual 12,000-mile round trip between Alaska and Baja California.

But the huge mammals that thrill so many whale-watchers are far from forgotten, especially at San Pedro’s Cabrillo Marine Museum, which stages its 20th annual Whale Fiesta on Saturday from 10 a.m. to 4:30 p.m.

Carnival games with whale themes, marine exhibits and talks by whale experts as well as the sculpting of a life-size whale in beach sand, combine to make the fiesta a way for families to have fun learning about whales and other sea life.

Larry Fukuhara, who directs the fair for the museum, said the event was started to celebrate the end of each whale migration season and is now more popular than ever. “There is a lot going on now in ecological and environmental awareness,” he said. “A lot of people are into whales and the ocean.”

Sculpting a whale in sand on the beach in front of the museum is the predictable highlight of every fiesta. People are invited to bring buckets and shovels and join in creating a 35-foot gray whale with its accompanying dolphins.

Carson High School teacher Bill Samaras will direct the band of impromptu artists as they turn mounds of sand into the figure of a whale. “He gets out there, maps it out, and tells people which end to build up, which end to tear down and when to smooth it out,” said Dan Zambrano, a museum aquarist who is helping put on the fiesta.

A city helicopter will fly over and take a picture of the finished whale and its creators at about 4 p.m. Zambrano said the museum keeps the whale intact for a couple of days, but “then wind blows it, people start walking on it.”

In addition to the large sculpting project, the museum will provide a special beach area for small children, so they can create their own little sand whales. “We hope to keep them from getting crushed in the melee,” Zambrano said.

Another outdoor whale will also draw those attending the fiesta, this time to the museum parking lot, where a 100 foot-long, life-sized blue whale will be painted on the macadam. A staff member has a Volkswagen Bug, a car that is the size of a blue whale’s heart. Of course, it will be parked exactly where the heart ought to be.

A special fiesta event at noon will be the official unveiling of a “spyhopping” gray-whale model as a permanent exhibit in the museum courtyard. The eight-foot tall model shows the life-size head of a whale as it pokes out of the water to look around, the behavior from which it gets its name.

“It’s anatomically correct, down to the barnacles, scars, the whole works. People can stand right next to it and run their hands over the barnacles,” said Zambrano.

Exhibits Director Mike Schaadt said schoolchildren already are fascinated by the new whale. “They go right up to it, touching it, feeling the barnacles and asking questions. That’s what learning is all about,” he said.

Children will be able to learn about whales by playing carnival games devised by the museum staff. Zambrano calls them entertainment with a little motivation thrown in. “They help people learn in a less frightening way. It’s a little intimidating to walk into a museum and see all the bones. We make a game out of it,” he said.

In one ring-toss game, youngsters learn about lice and other parasites that attach to whales by aiming their rings at simulated lice on a simulated whale. Another game relates to the squid diet enjoyed by sperm whales. In it, rubber squid are catapulted into a bucket, which represents a whale’s mouth.

Imagination will be rewarded in the “Great Cetacean Creation Sensation Contest,” which offers plaques as prizes for creative renditions of whales, dolphins or porpoises. Any kind of material may be used. “The only requirement is that they be less than four-feet long and free-standing,” Zambrano said. Entries may be brought to the museum until 10 a.m. Saturday.

In past contests, adults have entered exquisitely carved wooden whales or whales made out of stained glass.

“Children make them out of everything,” Zambrano said. “One little girl took two broken potato chips, and the way she arranged them, they looked like a whale.”

Rounding out the day’s events will be arts and crafts for children, museum presentations, food booths and the sale of sweat shirts and souvenirs. Members of the Los Angeles chapter of the American Cetacean Society, which is co-sponsoring the fiestas with the museum, will be on hand to tell people everything they want to know about whales.

Zambrano said the fiesta is “meant to be a family oriented day, where people can learn things in a very informal and fun way.”