I wrestle the big bull shark until my muscles are quivering with exhaustion. Just when I think I can't fight it another second, the line goes slack and I reel it to the side of the 16-foot boat.

Bull sharks, the meanest of a mean breed, are the most likely culprits in shark attacks against humans in these parts. Mine is 125 to 150 pounds, with such an ugly mug that I feel no guilt about luring it.

It would be hard not to catch fish in these teeming waters off the coast of Islamorada, the Florida Key known as the game-fishing capital of the world, a watery paradise where the Atlantic, the Gulf of Mexico and Florida Bay converge.

Plus I had a secret weapon, my own personal replica of Santiago in Hemingway's "Old Man and the Sea": Capt. Richard Stanczyk, of Bud N' Mary's Sportfishing Marina, a guy who reads the water like words on a printed page and says things like "See those currents?" or "See those brown ripples?" I, seeing nothing but the clear, baby-blue water of Florida Bay, cast my line where I am told.

Fishing is just one of many alluring outdoor adventures in the Keys, a collection of 823 islands — 30 inhabited — that stretch 108 miles along U.S. 1 from Key Largo near the tip of the Florida mainland south to Key West. Most of the area's 3.9 million annual visitors skip right over the other 822 islands and head straight to Key West. That's where the party is.

But I, on this four-day driving trip, found myself so in love with the Keys on the first 79-mile stretch, from Key Largo to Big Pine Key, that I never even made it to the primary tourist destination.

On Lower Matecumbe Key, I was waylaid by hundreds of tarpon, giant, prehistoric-seeming fishes that hang around the docks of Robbie's Marina, hoping for handouts from tourists.

On Grassy Key, at the nonprofit Dolphin Research Center, I spent more time than anticipated visiting Flipper's daughter and two of his grandsons, and even swam with some of the former movie star's more distant relatives.

On Little Crawl Key, I got caught in an almost spiritual experience as I joined the volunteers at the annual raptor count in the 1,000-acre Curry Hammock State Park. The volunteers let me use their binoculars as they tallied sightings of bald eagles, ospreys, falcons, hawks and kestrels that soared through skies of puffy white and blue.

On Key Largo, I had the honor of meeting Laura Quinn, a 77-year-old who shortly after retirement sold everything she owned to buy five acres of marshy land as a refuge for injured birds. There, in a tipsy house with a hospital on the ground floor, she lives alongside a huge collection of owls with broken wings, pelicans with cataracts and ibises with broken legs.

On Marathon Key, I got to feed Bubblebutt and Rebel, two of more than 800 sea turtles treated at the Turtle Hospital since Richie Moretti arrived there intending to retire. Instead, he ended up operating a 1950s-style motel to raise money to turn a topless bar into a high-tech MASH unit for the injured and sick turtles of the world.

On Little Torch Key, at Parmer's Resort, I got to know Amber, one of a couple of dozen exotic birds the hotel owner has rescued over the years. Amber, a pink, orange and white cockatoo, quietly puts her head to the side of her cage, begging to be stroked, unless you have the audacity to pay the slightest bit of attention to the other birds. Then she'll jump around and scream, "Amber's the pretty bird! Amber's the pretty bird!"

SWASHBUCKLING TALES

Over the centuries, the Florida Keys have been home to prehistoric tribes, swashbucklers, notoriously bloodthirsty pirates, bootleggers and salvage operators who made great fortunes picking over shipwrecks. Historic remains that can be visited today include what is left of wrecking stations on Indian Key, after more than 100 Indians in 1840 attacked the port settlement — then the county seat of Dade County.

Although the beaches on the Keys are few and small — the one at Bahia Honda State Park is the major exception — the islands have a Caribbean feel. Their reefs offer excellent snorkeling and, along with shipwrecks, great diving opportunities. Best of all, they have retained some of the flavor of old Florida. Some areas are as I imagine they must have been in the 1940s. Others must appear much as they did when Ponce de Leon sailed by, carrying home treasures from the New World.

More than a dozen parks and wildlife sanctuaries break up pockets of low-rise hotels and little B&Bs and campgrounds. Preservationists have, so far at least, done a good job of keeping the bulldozers at bay — creating, to my mind, the perfect balance of attractions and open space. Although hit by Hurricane Wilma shortly after my visit last fall, the Keys have largely recovered. "The tourism infrastructure is fully restored; all attractions are up and running," says Andy Newman, spokesman for the Keys Tourist Development Council.

The Keys are so laid back that there is no temptation to rush to see everything. It took me only a couple of hours to ease into the pace.

Here's how it went: On arrival in Key Largo, I headed straight to Strike Zone Charters on Big Pine Key and boarded a boat for a snorkeling tour. When we reached Looe Key National Marine Sanctuary, some of the other snorkelers took so long climbing down the ladder to the water that I had to exercise every bit of patience not to give them a right good push.

That evening, though, I suddenly realized I'd been idling a good five or 10 minutes at a stop sign, waiting without a care for a crab to cross the intersection.

It's that kind of place.

HERE FISHY, FISHY

Mike Reckwerdt, of Robbie's Marina, one day noticed a six-foot tarpon flopping on the beach. Reckwerdt put it in a concrete tank until a doctor could come by. The doc diagnosed a jaw plate so torn up that the fish couldn't eat, and jury-rigged a jaw hinge that he sewed into place with twine. Within a month, the tarpon had healed so well that Reckwerdt released it.

But the tarpon with the prosthetic jaw hung around. Soon he was joined by another tarpon, then another, and pretty soon Reckwerdt started selling small buckets of fish to tourists who came by to feed them. And that is why today hundreds of tarpon hang around Robbie's Marina. There is something mesmerizing about watching those tourists who, instead of tossing bait, lie on the deck and hold the little fish within fractions of an inch of snapping tarpon jaws lined with sharp, sharklike teeth. It's like waiting to see an almost-certain train wreck.

You might conclude, after a few days in the Keys, that there's something about the place that encourages a charming eccentricity.

Like the bar patrons who started pasting dollar bills to the walls and ceilings of the No Name Pub on Big Pine Key, where tourists and locals alike sit and conjecture about how many tens of thousands might be hanging all around them.

I stopped at the pub after driving into the area to see key deer — a small breed that, when full-grown, are the size of Bambi. I ended up sitting next to an old guy who lives on his boat nearby, and I mentioned that I'd seen only a few of the deer on my drive.

"You want to see a lot of key deer? Plant a garden," he said.

And then there's Moretti, the owner of Marathon Key's Turtle Hospital and the adjoining Hidden Harbor Motel. He bought the motel along Florida Bay, intending to tear it down and build his dream home. Before he got around to that, though, he ended up taking in some injured turtles. Soon he found himself renovating the motel to raise money for more and more turtles, which he says are shipped to him from around the United States and the Caribbean. FedEx and American Express do the transport for free.

Hidden Harbor was hit by the hurricane and has yet to reopen. However, the hospital is open for tours, and visitors can stand for as long as they like along a large pool filled with a couple of dozen turtles. Most will be freed after they heal. Then there are the permanent residents, like April, Bubblebutt and Rebel.

April is blind, so workers at the hospital bang a metal hook to let her know it's feeding time. She comes near the sound, opens her mouth and waits for food to drop in.

When a turtle's shell is broken, it cannot swim beneath the surface, even after the wound heals. Bubblebutt, a 70-pound green, and Rebel, a 225-pound loggerhead, are permanent residents because they have to wear weights on their rear ends; otherwise they'd float to death.

Most of the turtles that come here have been injured by human thoughtlessness — like carelessly tossed fishing line or other garbage, particularly plastic. Vets at the Turtle Hospital once found 325 cigarette butts in one turtle's bowels. One turtle couldn't survive the garbage in her gut, including a piece of metal stamped "USA" and a plastic bag made in Australia. Said Moretti, "It took at least two countries to kill her."

FLIPPIN' FOR DOLPHINS

The 16 bottlenose dolphins at the Dolphin Research Center could easily have headed to sea during Hurricane Wilma as 10-foot water surges overwhelmed the fencing in their lagoon. But as in past storms, they all chose to stay.

The research center is one of five facilities in the Keys that offer dolphin observation and swimming with dolphins. Three are licensed by the Alliance of Marine Mammal Parks and Aquariums — the minimal credential I'd demand before even considering participation.

I have qualms about keeping gorgeous wild animals in captivity and about swimming with dolphins in general. But my unease lifted when I saw the natural waters available at the Dolphin Research Center and witnessed the research and public education efforts aimed at protecting dolphins in the wild. Fees from tourists subsidize the $80,000 it costs per year to feed and care for each of the dolphins at the facility.

Purists could argue that the dolphins stick around willingly because, conditioned by the free food, they've adopted a slave mentality. But who am I to question the choices of a dolphin?

None is forced to swim with the small groups of tourists allowed into their lagoon at specified times. Trainers hold up symbols that represent the names of those invited to swim with humans during a given session, and if they want to come, they do.

All four dolphins invited to swim with my group of eight responded to the calling cards, and for 25 minutes we had the great privilege of frolicking in the water with what I consider to be the most graceful and beautiful of all sea creatures.

The dolphins here each know up to 100 commands and sometimes teach each other moves and tricks. We got to stroke their smooth bodies, and each of us had a turn performing with a dolphin: The trainer gave them the "imitate" command and then, whatever each swimmer did, the dolphins mimicked. I took water in my mouth and spewed it in an arc, and soon found my face covered with the water that the dolphins spewed at me. One human in my group twirled, and the dolphin twirled. You jump up, they jump — only higher and more gracefully.

The grand finale: I floated stomach down, legs extended, head up. Two dolphins, each with its nose against one of my feet, pushed me around the lagoon.

The research center was home to the original Flipper, back in the days when it was Santini's Porpoise Training School.

Actually, though, Flipper was three different dolphins. Mitzi, who had a very pretty face, played Flipper in all the close-ups, but she wasn't the most athletic of dolphins. She therefore had two stunt doubles, Little Bit and Mr. Gipper. All three were trained by founder Milton Santini, a commercial fisherman who got into the dolphin business after accidentally netting and injuring one. During the dolphin's recovery, the two mammals bonded and Santini found a second career.

In the 1970s, the facility was taken over by a marine mammal scientist. Today it's both a research and a rescue center for injured dolphins and manatees.

Mitzi is, sad to say, long gone. But Little Bit and Mr. Gipper had a daughter, Tursi, who is now 32 and still lives at the center, along with her two sons, Pax and Talon.

Tursi, by the way, is a great jumper, but terrible at math. Talon, however, is a math wiz, routinely scoring 80 percent or better on exams that are part of a project to prove that dolphins understand numerical concepts.

I spent much of my childhood wishing I could live in a place like the one where the boys in "Flipper" lived, and wishing I could ride the waves with a real live dolphin.

And for a short time, at least, I found myself in the Florida Keys, living the dream.