Despite the punch of the rum cocktail and the lure of the beautiful resort and its private bungalows, I'm determined to paddle back to my base on Union Island before nightfall. Pocketing the shell, I head to my kayak. Fifteen minutes later, a pair of tall, bare-chested, dreadlocked men welcome me to a much different isle.

Happy Island is minuscule and man-made from rocks, Portland cement, and huge pink conch shells. It's late on a Caribbean afternoon, the sun starting to slip toward the horizon, but Janti, the island's owner, and his co-worker Roderick are still hard at work. Between puffs on a giant yellow-papered fatty, they are mixing cement, completing a half-moon wall surrounding a saltwater fish and lobster tank.

Taking a break, Janti reaches behind the bar and brings out a stack of photographs showing the six-year history of the island, a little tax-free paradise that is both his home and business, within striking distance of Union Island's yachties and main town. He is not explicit about how he's managed to build an island in the heart of the busy bay. "I didn't ask anyone," he says. "I just started one day, and no one's ever asked me to stop."

Teetering on the edge of the island is a two-room building made of wood and cinder block, its sole structure. One room is a combination kitchen and bedroom; the other is the bar: Its floor is sand, its chairs are plastic, and the bar itself is covered with half-filled Coke, rum, and Fanta bottles. Reggae issues forth from a pair of giant speakers stuck into the sand, and a welcome late-afternoon breeze rustles the recently planted palms, just six feet tall.

This is my kind of place. For an hour I help the two men mix cement, and pay four dollars for a rum punch the equal of the one I had for thrice the price back on Palm Island, though I imagine that Happy's overhead is much, much less.

So far, the island has been hit just twice by hurricane-force winds, but it seems a statistical certainty that Janti will one day have to deal with the big one. For now, though, he's content to spend his days collecting conch shells and mixing cement.

As I climb back into my kayak, I'm glad to know that Happy Island exists; it smacks of rebelliousness. I ask Janti if he envisions being here for many more years. "I really don't look much further than tomorrow," he says.

After nine days and six islands, the marine reserve at Tobago Cays is my last stop in the Grenadines. Protected by Horseshoe Reef, the marine park comprises five uninhabited islands. From my kayak I see sponges, colorful coral, parrot fish, grouper, trunkfish, and a six-foot nurse shark.

I go slow, my eyes peeled for the reserve's green turtles. Buoy markers carve out a sanctuary within the sanctuary for the turtles; a Union Island taxi man named Taffa told me that they also serve as markers for poachers. "Sometimes the bad boys come over, dive in, and take the turtles anyway," he said.