See the rain forest from within

A 30-foot tree fern crowned with a cluster of eight-foot fronds looms over our heads. Orchids and bromeliads cover the trees, and a curtain of vegetation hides the sky so only slivers of light filter to the forest floor. I find myself glancing through the Jurassic scene wondering if a dinosaur might rear its head from the shadows.

Across the steep valley we glimpse a rugged mountain ridge with four peaks. Clouds drag bottom as they sweep across Mt. Gimie, the highest point on St. Lucia, an island member of the British Commonwealth in the southeastern Caribbean.

Mahogany, kapok, strangler fig, and a host of other trees create the canopy that shades our hike. In places, the slope drops hundreds of feet on either side.

After an hour of constant descent, we reach a meandering stream and climb down a long wooden staircase to the Enbas Saut Waterfall, a 30-foot cascade with an inviting plunge pool.

Rain forest covers St. Lucia from the 3,000-foot peaks down to a coastline scalloped by pocket coves with black-sand beaches and coral reefs.

We quickly discover that traveling in a straight line, whether by trail or road, is impossible on an island dissected by precipitous mountains. The road to the trailhead from Soufrière winds seven miles up the mountain and takes 30 minutes of stop-and-go driving.

The Forestry Department maintains the 19,000-acre Rainforest Preserve with trails that vary from our three-mile loop to a 10-mile one-way excursion.

Without Pam Alfred, the trained guide provided by the Forestry Department, we would miss many of the highlights of the rain forest. A 23-year-old championship cricket player, Ms. Alfred points out a land crab. It waves its pinchers menacingly when we stoop to observe.

In addition to ferns that grow into trees, St. Lucia has palm trees that masquerade as vines and twine up other trees. Or they mimic pincushions. Needlelike spines cover the trunk of the gui-gui palm, locally called the "ouch tree." We stop frequently for glimpses of the St. Lucia warbler but listen in vain for the rare St. Lucia parrot.

Though only 27 by 14 miles in size, St. Lucia harbors 165 species of birds, four of which live nowhere else on the planet. More than 1,400 types of trees grow on the island, compared with about 680 species native to North America. Turtles nest on the beaches, and seabirds colonize rugged offshore islands. Reefs and shoals rich with marine life surround the island.

The islands of the Lesser Antilles were born from fiery eruptions some 240,000 years ago. The volcanic past of St. Lucia created the two most famous icons of the island, the twin Pitons. The ancient remains of the two volcanic plugs rise more than 2,000 feet straight from the aquamarine water.

Jalousie Bay, one of the small, picturesque coves that line the western shore, sits between the Pitons. We catch a water taxi from our hotel to Anse Chastanet, a resort in a nearby cove that offers jungle biking.

The water taxi drops us off on an isolated beach at the mouth of a narrow valley. A broad trail leads to the place where we rent our suspension bikes. "During the 18th century, this valley was a 400-acre French sugar plantation," says Michael Allard, director of Bike St. Lucia. "We'll pass some of the stone ruins. We carved eight loop trails totaling 10 miles through the jungle. The difficulty ranges from beginning level to world-class competition."

We strike out on the Riverside Trail, rated green for easy. "We designed our beginner trails to be ridable for the inexperienced, but a challenge for those with more technical skills who want to take it faster," Mr. Allard says.

After strenuous biking through the jungle - sometimes twisting around corners, then plunging 30 feet downhill and back up a steep incline - it's time to relax. We take a refreshing plunge in the surf. The alchemy of the setting sun transforms the volcanic sand from shimmering silver to gold. No roads lead to this cove, or to the many finger bays on the western shore. We have the beach to ourselves.

Come Friday night, the nearby village of Anse La Raye barricades one of its three streets, and the locals grill the day's catch at the curbside. This weekly street party is a longstanding tradition. It offers succulent fish, lobsters, floats (fried dough), and bakes (flat bread). Foil-wrapped dinners of steamed flying fish, red snapper, mahi-mahi, or octopus start at $1.

As the night progresses, hundreds of people crowd the street, and music drowns out the sound of the surf one block over. No one hassles us or makes us feel uneasy. "You're not foreigners," a Rastafarian man tells us. "The only thing foreign is something that separates your heart from God."

It was the perfect end to our weeklong getaway.

With its tropical rain forest, multiple adventure activities, and cultural flavor and hospitality, St. Lucia redefined the surf-and-sand image we had of a Caribbean holiday.