Swimming with shark...an exciting experience!

JUST after 6 a.m., I awoke to the sound of someone chanting my name. Peeling back the side curtain of my upper bunk, I was greeted by the wide-awake face of Alan De Herrera, trying to roust me from the cubbyhole where I had been holed up for the last 10 hours. It had been a rugged 22-hour steam by boat from San Diego, about 215 miles away.

Ten-foot swells had resulted in a stomach-churning side-to-side tottering, but somehow, overnight, hunger had replaced nausea. The Mexican sunrise anointed me when I ascended the stairs. Less than a mile away, I could see Guadalupe Island, host to one of the world's largest aggregations of great white sharks.The reason I was here.While we ate, our vessel, the Odyssey, maneuvered to the northeastern, leeward side of the island, anchoring about 200 yards off an area nicknamed "Shark Heaven."

We had signed on with Patric Douglas, a veteran of shark-diving operations and the chief executive of Shark Diver, which offered this five-day, live-aboard package. Guadalupe, 19 miles long and five miles across at its widest point, is a pinniped sanctuary: Northern elephant seals, Guadalupe fur seals and California sea lions congregate at rookery and haul-out points around its perimeter. Abundant yellowfin tuna and yellowtail also attract sport fishermen.

In 1998, long-range fishing boats out of San Diego began reporting great whites attacking their catches.Word spread like chum.Keep hands inside the cageTRACY ANDREW, our dive operations manager, laid down the rules with disarming authority: Never stick any part of your body outside the cage, and never make any sudden movements that might trigger a "predator-prey reaction," she said at the dive meeting.

Tracy would monitor us from the dive platform. Another "sharky" would man a push-pole during rotations. "If a shark were to come in too close to the cages, we push it off," Tracy said. "It doesn't harm the shark. We just give them a little extra nudge to keep them from entering the cage, because sharks don't have a reverse mode." I was the only noncertified diver which was why Patric had emphasized taking a pre-trip introductory scuba course. "Some people get claustrophobia or panic," he had told me.

"The last thing you need to worry about is breathing through a regulator with great white sharks swimming in your face."Noncertified divers are allowed because you don't go deeper than 10 feet (the height of the cages) and breathing is done through a "hookah," a regulator on the end of a long hose connected to a shipboard air compressor.We were divided into two teams — Black and Blue — of eight divers per group. Each team was further halved into A and B, designating starboard and port cages, respectively.

Teams would alternate one-hour dive rotations. There were 11 crew aboard (usually there are nine) and 17 divers, including Mauricio Hoyos Padilla, a 28-year-old shark researcher from La Paz, Mexico. Patric has been an ardent sponsor of Mauricio and other shark researchers. "Something truly special is happening at this island," Patric said as we waited for the seas to abate enough to dive, "and I believe it's absolutely incumbent for any eco-tour operator to give back or channel funds into any sort of research going on.

But without direct engagement with the Mexicans, we will lose this site."Guadalupe is protected as a marine biosphere reserve, but so far little has been done to manage or police it. Trophy hunters and fin raiders prowl the waters. "One set of great white fins on the open market today is worth upwards of $25,000 — $5,000 a fin, plus jaw," Patric said. I was assigned to Black A Team, along with James Mott, a guitarist in a punk band called Casket Gasket from Farmington Hills, Mich.; Ken Steil, a young Detroit police officer; and Alan, a friend from Fullerton who is a nature filmmaker and was here for the second consecutive year.

His intense shark footage had persuaded me to come see them for myself. At 1 p.m., we were cleared to dive. The two cages were winched off the starboard side and carefully worked toward the stern. Hang bait, 5-gallon bucketfuls of tuna parts, and powdered chum — made from dried fish and blood meal — were tossed into the water. I wrestled into my borrowed wet suit, then the head-shrinking hood, the boots and gloves, and I felt as though a black python had me in a goodnight squeeze.

Down on the dive platform, a sharky threw a 60-pound weight harness on my shoulders, cinching the belt snug while I fought off waves of claustrophobia. "Show me how to purge your mask," Tracy said, making sure I was ready for my first open-water dive. I obliged, then sat on the dive platform. We timed my entry between rogue waves and surges. I thrust the regulator in my mouth, threw my legs into the lurching cage, and — KER-PLOOSH!

When the bubbles cleared, I was standing on the cage floor. Tracy's blurred face peered down at me. Her hand was underwater giving me the OK sign, which I returned. I got tossed around a bit trying to fight the currents until I realized the idea was to stay loose, knees bent in a boxer's stance. Visibility was 25 feet, well shy of the usual 80-plus feet. A plankton bloom was turning the blue water green and dusky. The rest of Black A Team already stood in shark-watching position, camera-wielding sentries each facing a different direction.

Standing in the cage weighted to negative buoyancy felt like being on the moon at one-third gravity, except the hazy green cosmos was inverted. We waited. Ten, 20, 35 minutes. No sharks. Then Alan was pointing to our left as part of the sea separated from itself, becoming a gray-green plasmatic specter that took form.A cruising killing machineNO "Shark Week" on Discovery Channel could have prepared me for the overreaching immensity of my first carcharodon carcharias rising from below, 3,000 pounds and 15 feet of shark nearing our titanium-reinforced aluminum cage.

Sun shimmered off the great white's back like lightning flashes as the titanic fish moved with eons of evolved efficiency. Even at first sighting I knew its design could not be improved on. Not as a cruising killing machine. The low visibility, along with a great white's notorious ability to appear to change hues — different combinations of blue, silver, charcoal gray, sea green and bronze — allowed the shark to manifest like a haunting: near the surface one moment, right under the cage floor the next.

The spookiest was when it assembled from phantasmal mist in the near distance, becoming as solid as a fanged U-boat as it came at us. The preternatural girth of the animal — 8 feet or so — reduced me to an awed simpleton. A metallic clinking from above signaled our hour was up. Topside was bustling with divers, crazed with excitement now that the first great white had made contact. There would be only one rotation per team today because of the weather-delayed start. The great white that cage-stormed us was Scarboard, a female named for the distinctive scars on her right flank.

Both males and females are often scarred, and some are missing chunks. Violent territorial infighting is common. These white sharks spend at least half the year in open waters between the California coast and Hawaii, but what they're doing out there remains a mystery. Nor is it fully understood why great whites converge on Guadalupe Island every year as fall approaches. Mauricio theorizes there may be a correlation between elephant and fur seal migration and breeding patterns.

Elephant seals are a white shark's favorite food. Male white sharks first appear in early July, and larger adult females begin showing up around September. The largest shark observed by scientists and eco-tour operators in the area was 16 feet, but local fishermen have reported sharks as long as 20 feet. The water was pimpled with whitecaps the next morning. During the dive meeting, Patric reinforced safety protocol, cautioning us that loading in and out of the shark cages would be interesting today. (As if it hadn't been yesterday.)

After breakfast, Blue Team took the first dive, at 7:30 a.m. The water had a blue tinge to the algae green, which meant visibility was now approached 40 feet. No great whites were sighted all morning, so I decided to skip the afternoon's rotation and take some notes. That's when the shark came. My teammates came up stoked about a 13-foot male that made some harrowing cage calls. I felt like Charlie Brown on Halloween after a night of trick-or-treating. Charlie's friends gets bags full of candy; he gets only a rock.

Except in my case it was plankton and chum.A queen beastI was awakened the next morning by a loudspeaker announcement that dive rotations would start an hour earlier because conditions were optimum. The sea had turned a docile blue overnight under wind-cleansed skies. Black A Team cracked first descent. We weren't bullied by currents in the cage, and visibility was 60 feet and improving. But our first two rotations brought no sharks. At midafternoon, two fishermen in a panga skiff slid up on the Odyssey's starboard.

The West Anchorage on the island's windward side is a seasonal fishing camp for the same returning consortium of Mexican fishermen and their families who spend 10 months harvesting Guadalupe's abundant abalone and lobster, which is shipped back to Ensenada, where most of them come from. Patric ritually offers them a few supplies, such as fresh vegetables, meat, batteries, sodas and fishing gear, to maintain good relations. The fishermen, in turn, have become invaluable aids to shark researchers such as Mauricio, motoring him around the island to follow tagged sharks' transmitter signals.

He boarded the skiff toting a directional hydrophone and receiver and putt-putted away.At 4 p.m., Black A Team loaded into the cage for our last dive of the trip. A 14-foot female materialized from below the Odyssey's hull. She passed close enough for a pectoral fin to rattle the cage bars. As she receded, another great white, also a female, eclipsed my mask window. She swam beneath the cage and ghosted away. Both sharks were hidden, but you could feel them out there. Then, movement erupted from the starboard.

The new shark was a giantess, lingering under the panga. Her dorsal fin surfaced. I would have figured her size was some freak underwater refraction, except that her body ran the length of the panga, about 18 feet.The queen beast, easily 2 tons, glided on pectoral wings, moving to the hang bait that floated just below the surface off starboard, mouth toward us as it yawned open. The upper lip crinkled back, revealing bloody gums and a bony ridge filled with what looked like layers of broken razorblades.

The cavernous passage to her gullet waited. She tore the bait from the line with a fierce swipe of her head and continued toward us with a slack-jawed grin. She moved in along the cage, taking a good look inside. Her right eye was fathomless, landing on me like a dual judgment from God and Old Scratch. I was looking into an omnipotent black hole that slung me back 11 million years, where nothing was ruined.

*How to get started and what to take GETTING THERE:Boat charters leave from Fisherman's Landing in San Diego Harbor, a five-minute cab ride from San Diego International Airport.

THE TRIP:Ecotour operator Patric Douglas offers five-day live-aboard packages during great-white high season, which starts in September and ends in early December. Rates start at $2,650 per person. Shark Diver, (888) 405-3268 or (415) 235-9410, http://www.sharkdiver.com . The vessel we went on was the Odyssey, but this year, Douglas has changed to the Islander, an 89-foot craft with private air-conditioned staterooms.

GEAR AND OTHER INFO:Water temperatures at Guadalupe Island can range from 61 to 74 degrees. Some divers use dry suits, but I felt fine in a 7mm. (Our water temps were on the low end.) Hood, gloves and boots are definitely in order. If you don't own an underwater camera or housing, underwater disposables work fine at close range. (Shark Diver can assist with rental of personal dive gear.)

A live-aboard charter means you never leave the boat, except to get in the water, so be prepared to exist in an enclosed space with about 15 other passengers and nine crew members. Bring something for distraction; there is plenty of downtime after the dive day ends. Fishing is encouraged. During our trip, sheephead, California whitefish, yellowtail and squid were caught. For noncertified divers: Although scuba diving is not involved, you should get the feel of breathing through a regulator, either through an experienced friend or an introductory scuba discovery course at your local dive shop.

Also, getting comfortable with all the gear beforehand greatly boosts preparedness. I watched TV with my mask on, breathing through a snorkel to get used to controlled breathing.