When Paul Woodard and I sailed our 41-foot yacht Felicity from the U.S. East Coast to Tahiti, our voyage was a relative piece of cake -- until we came to the great line of atolls known as the Tuamotu Archipelago. Like a fence stretching for 1,159km (720 miles), the Tuamotu islands block the northeastern approaches to Tahiti. They are so low -- never more than 3m (10 ft.) above sea level, not including the height of the coconut palms growing all over them -- that hundreds of yachts and ships have been wrecked on these reefs, either unable to see them until it was too late or dragged ashore by tricky currents swarming between the islands and ripping through the passes into their lagoons. Those of us who go down to the sea in yachts well understand why the Tuamotus were once known as the Dangerous Archipelago.

Needless to say, Paul and I had to be on our toes when navigating these waters. While he signaled me from the bow, where he could more easily see coral heads in the water, I steered Felicity through narrow Tiputa Pass and into the lagoon at Rangiroa. Once safely inside, the calm water made it seem as if we had sailed into a monstrous lake in the middle of the South Pacific Ocean.

Like all atolls, those of the Tuamotus are necklaces of perfectly flat islets enclosing crystal-clear lagoons. Consequently, they offer a very different kind of experience than French Polynesia's high, mountainous islands. You will find many black-pearl farms (most of the country's orbs are produced here) and small villages with whitewashed churches, but there is much less to be seen aboveground than there is underwater.

Sharks, rays, and more than 400 species of colorful tropical fish inhabit these lagoons, making for French Polynesia's finest snorkeling and scuba diving.

Of the 76 atolls, only Rangiroa, Tikehau, Manihi, and Fakarava have accommodations up to international standards; accordingly, they are the most visited. Only yachties and a few other intrepid travelers go elsewhere.

You will find drier and hotter climes than in the Society Islands, and sand so brilliantly white that it alone requires sunglasses in the midday sun. So grab your hat, your snorkeling gear, and your fins. Those of us who love the water are in for a treat up here in the Dangerous Archipelago.