Daylight streams in from an opening, illuminating the triangular shape of the "shark's tooth." We haven't paddled into Jaws. We're exploring one of many sea caves that cut into the coastal bluffs of California's Santa Cruz Island. Our predator? A jagged rock formation hanging from the ceiling.

Santa Cruz sits 19 miles off the harbor of Ventura, California, in the Channel Islands National Park. Like the park's other four islands, it shares a steep, rugged topography defined by sharp spines jutting from the ocean. The easiest of these islands to reach, Santa Cruz is a one-hour, $48 round-trip ferry ride away. Its attractions fulfill any nature lover's wish list: sea kayak trips, scenic hikes, and full-blown camping expeditions with plenty of free time to explore.

Although no one aside from semipermanent park rangers currently lives on Santa Cruz, I'd been inspired by images of ancient Chumash people, the islands' original inhabitants, paddling carved wooden boats on fishing and hunting forays. I knew that to really experience this place, I would have to hit the water.

The park boundary extends a mile offshore, protecting one of the world's richest marine sanctuaries. After basic kayaking instruction, I slide my sit-on-top boat into the ice-cold sea. Soon I'm gliding over a kelp forest as ecologically diverse as a tropical rain forest. Bright orange garibaldi fish hover 10 feet below. Curious sea lions surface and stare like wide-eyed toddlers.

Giant caves open into the volcanic cliffs, eroded by heavy surf over thousands of years. The biggest ones spread wide like dark, flooded theaters with stages of gray, purple, and sea-green boulders the size of beach balls. Moving from cavern to cavern, I enter a tight cave with shoulders pinched, headlamp lighting the way. The surf gently carries me into an open room, a sea-cave cul-de-sac. 

It's hard to believe that the rock formation above is actually the bottom of an island mass. Returning to wide-open blue sky and water, I feel as though I've emerged from a secret hideaway. With guidance and a bit of acquired balance, I've experienced the thrill of floating over a forest, through a cliff, and beneath a treasured island.

The lowdown on a Channel Islands excursion:
Aquasports: 800/773-2309 or islandkayaking.com.