Standing on a low cliff, the guide was praising the turquoise waters just below as the best spot for our after-lunch snorkeling.

“Monsieur,” a tourist called out, pointing. “A shark!”

“No, no, this area is perfectly safe,” he cooed without looking. “You will have comfortable waters with abundant – ”

“There it is again!” someone interrupted, and the crowd surged forward murmuring. The guide wheeled his head just as the unmistakable dorsal fin of a midsized reef shark broke the surface a third time. “Whoa!” (or some French equivalent) cried the vacationers.

The undeveloped, low-lying islands of Petite Terre in the French West Indies were proving a little more “natural” than even the brochures had promised. I was with a group of 24 who had traveled here from Guadeloupe on a luxurious catamaran, the Tip Top One.  Once ashore, though still perfectly safe, we felt we were in an almost prehistoric land.

This French national park in development is the world’s last sanctuary for the Antillean iguana, and I ran into a dozen of them. (On other Caribbean islands, the species is extinct, endangered or threatened.) They look scary, like scale-model dinosaurs, but being vegetarians they have no interest in bothering people.

The iguanas sunned themselves along a “history trail” that provides glimpses of mid-19th-century human habitation, including a working lighthouse.

A few families used to eke out a living on these dry, rocky islets.  But not a soul has lived here since 1972 when the lighthouse was automated.  Around the lighthouse were fake-looking plants – agave – whose long straight stems are topped by a few spindly branches like those cellphone towers disguised as oddly proportioned evergreens.

The guide said strictly enforced park regulations had unexpectedly cut down the   sightings of one species. Tour-boat crews used to feed a particularly large sea turtle, but when they were no longer allowed to do so, the turtle got “attitude” and refused to show its face.

My actual snorkeling proved a little disappointing. I tried it where the guide had recommended (the sharks on these reefs are quite safe as long as you don’t bother them). But the spot I was in had no coral and few fish. Other guests reported better snorkeling back near the boat.

Besides its educational value, there are other advantages to this day trip ($140 per person) a few miles off Guadeloupe’s eastern tip. Food is one.

After we had spent a couple of hours exploring the island, a rubber dinghy returned us to the catamaran for a healthy lunch served on china.

First, a large – nay huge – tub of crudités arrived at each table of six. The main course was dorade (mahi-mahi) with rice and a tasty vegetable sauce. Mangoes, guava and other tropical fruits were passed for dessert. Bottles of wine kept coming, and one French tablemate kept out glasses full with ceremony and enthusiasm.

A spot of liqueur ended the meal. “Eat, drink, eat, drink – that’s all we do,” one woman happily exclaimed.

Parties aboard other tour boats had their lunches on the beach – one in an elaborate portable pavilion. But I was grateful for the sand-free dining with real glassware.

Then the dinghy ferried us back to the beach for an afternoon of sunning, swimming and snorkeling. We made an unexpected detour when the crew member manning our boat thought it would be funny to make a gallant show of returning to its owner a bikini top we found floating. The woman was sunbathing French-style on a nearby yacht in the mooring area between the two islands. She laughed cheerfully as her male companion received the delivery.

The first thing I saw back on land was just as funny. A convention of hermit crabs in ridiculously mismatched “hats” was scavenging the remains of one those beach picnics, oblivious to each other’s fashion faux pas.

If your dream is an untouched tropical island, this could be it. It’s so untouched that you notice the human interventions, like the Hollywoodish cluster of palm trees on one end. The Photoshopped-in look is a reminder that, like all coconut palms in the Caribbean, they were imported from Asia.

The afternoon ended with a smooth, 90-minute crossing back to St. Francois. On a nearly windless day, our trip was motorized, without sails.

In the morning, the music on the sailboat’s speakers had been mellow – Bob Marley and other island sounds. By afternoon, it was party time with rock and hip-hop, and the crowd stayed with it. One rap song, “Life in the Ghetto” had particularly depressing lyrics (“Whoever said this struggle would stop today … Teenage women growing up with AIDS”), but I don’t think anyone else on board understood English.

Views of the craggy rocks of Pointe des Chateaux at Guadeloupe’s eastern tip were spectacular. It was also fun to look down. The sailboat had two large net trampolines where travelers could take turns lying and relaxing — just a couple of feet above the azure sea rushing beneath.

Happy traveling!

Captions: 1. Tip Top One’s large, comfortable catamarans ferry passengers to Petite Terre in style. 2. Prehistoric-looking iguanas are actually vegetarians, and have only two predators – people, and each other. 3. No one has lived on the islands since 1972, when the lighthouse became automated. 4. One of Tip Top’s advantages was a delicious meal served family-style on the comfortable, covered boat deck. 5. A gaggle of hermit crabs cleaned up after another group’s picnic on the island. (Photos by Thomas Simonet)