SUMMERTIME : Discoveries : If you’ve exhausted the usual tourist spots, here are some destinations off the beaten path. : In Search of the Creature of Lake Castaic

She’s not quite the Loch Ness Monster, but somewhere under the placid waters of Lake Castaic swims a creature that has the fishing world quivering in its hip boots. When she is eventually dragged from the lake in what promises to be a violent fight, the news will be trumpeted across the covers of outdoor magazines from here to Georgia.

The creature is a largemouth bass. She eats rainbow trout. She will weigh more than 22 pounds and be as big as the largest watermelon. And she will eclipse George Perry’s largemouth bass world record catch of 22 pounds, 4 ounces, a fish hauled from a Georgia pond on May 19, 1932.

Now the bad news: It is highly unlikely that you will be the one to catch the mammoth bass, a fish that could bring her conqueror as much as $1 million in fishing tackle endorsements. The massive fish will probably be fooled by a pro, one of several dozen full-time, fanatical anglers from around the nation who have been whipping the lake’s surface into a froth each day for months, trying to entice her (the largest bass are always females) into attacking one of their lures. The anglers have been lured onto the lake because of its reputation as a giant bass producer and also because of the 60th anniversary of Perry’s catch and the fame and fortune that will visit the person who breaks that record.

Fishing pros are firm in their belief that a 23-pound and 24-pound and perhaps even a 25-pound bass roams the depths of the lake, which is 20 miles north of the San Fernando Valley on Interstate 5.

People who don’t have the endless hours it takes to chase down a world record fish--or don’t enjoy the thought of being yanked headfirst into the lake by a fish that can generate enormous power--can still fish at Castaic.

Throughout the summer, trout are available. They are often caught from shore in the early morning and late afternoon, and all day in deeper, cooler water from boats. The Department of Fish and Game regularly stocks the lake with 12- to 16-inch trout.

Even on your best day, however, you won’t catch all of the trout.

Bass of 14 and 15 pounds that are caught with some regularity often have trout in their stomachs, and some anglers fish for the giants with lures that imitate the trout.

Giant catfish, often weighing eight or 10 pounds, are also caught regularly from shore even during the hottest months.

Rental boats are available at the lake, which also has a complete bait and tackle shop. The daily entry fee to the lake is $5 per car. Call (805) 257-2049.

Another 10 miles up Interstate 5 sits a more scenic spot, Pyramid Lake, that offers trout fishing throughout the summer amid the splendor of the Los Padres National Forest. But perhaps the most remarkable thing about the fishing at Pyramid is the abundance of an even more aggressive fish: the striped bass. The fish is native only to the Atlantic Ocean, but striped bass eggs and fry were transported across the country by train at the turn of the century and released into San Francisco Bay.

The fish flourished in the Pacific and moved far inland via the Sacramento Delta System. When the Los Angeles Aqueduct was opened and began pumping billions of gallons of water toward Los Angeles, it also sucked millions of striped bass eggs and fry into the system. Pyramid Lake, being a terminus for the aqueduct, soon had a thriving population of the fish.

Stripers of 25 and 30 and even 35 pounds are caught with great frequency at the lake.

Rental boats are also available at Pyramid Lake, in addition to bait and tackle. Daily entry fee is $4 per vehicle. Call (805) 257-2892.