Here's the thing about St. John. When your ferry docks in the capital of Cruz Bay -- there's no airport -- the town seems deliciously quiet and slow-paced, a refuge for urban escapees. But spend some time in the island's interior and you'll discover the real meaning of slow: feral burros and goats wandering the roads, sugar-shack bars, eco camps with rainwater showers. Turns out that Cruz Bay, with its hip boutiques and seriously upscale resorts, is actually quite the hotspot.

Arriving without a plan, my traveling companion and I surveyed the scene. Which St. John was it to be? Peaceful, environmentally correct campsite, or luxury villa by the sea?

Both, of course.

The Concordia Eco Tents compound, about an hour from Cruz Bay on St. John's remote southeast coast, is legendary among the backpack set. In the mid-1970s, New York developer Stanley Selengut started his eco-empire with 11 self-sustaining units at Maho Bay. Concordia soon followed, using solar and wind power for electricity, roofing materials that reflect heat and a sensitive design that minimizes the developments' impact on the land. They're still popular, and not just because they're PC: At $75 to $95 a night, they're a fraction of the cost of chi-chi resorts.

Our "tent" was actually a wood-framed, canvas-sided structure with windows, a screen door and a balcony, tucked away on the mountainside and reachable via a series of wooden decks and 104 (!) steps. We couldn't see our neighbors, although we did hear guitar licks wafting out from one of the other cabins as the light began to fade.

When the sun sets in the Caribbean, it sets fast. It was too dark and scary to drive back across the island in search of supper, so we dined that night on a battered pear and part of a sandwich left over from lunch. We ate it on our balcony overlooking Salt Pond Bay, staring up at the stars and wondering what that dark shape was that kept creeping up to our cottage.

In the morning we had a better look around our mountain aerie. The cottages are ingeniously designed, with wide deck flooring, space-agey white roofs, large screened windows and those balconies with killer views. The kitchen area comes complete with running water (cold only) and a battery-powered eco-fridge that never got the Cokes above tepid. Not surprisingly, there are no TVs, phones or air conditioners in the rooms, but each bed sports a solar-powered mini-fan and reading light. An ominous-looking battery thing constantly warned that we were in danger of losing power during our two days there (we never did).

In the bathroom, a solar-heated, glass-topped shower drew rainwater from a plastic barrel on the roof. "Pump yourself a warm, refreshing, no-cost shower!" exhorted a nearby sign. "In the morning: Gently pump rain water from your cistern into the black barrel located on the roof of your shower. Count 20 strokes per person . . . Conserve water by not leaving the water running. Wet down, soap up, rinse off. A natural shower from the sun and the rain!"

I ventured in and started pumping. Yow! Why was the water so cold?! It finally dawned on me (literally) that if you get up early and it's been dark for the previous 12 hours, the water isn't going to be hot. Note to self: Take shower at night.

Visitors to Caribbean islands invariably get tangled up in synonyms for blue when trying to describe the water. In St. John, that honor goes to green. The foliage-draped mountains, in varying shades of emerald, moss, lichen, kelly, loden and chartreuse, command your attention before you even notice the clear blue sea. Fully two-thirds of the island is national parkland, crisscrossed by more than 20 miles of trails.

Driving is the best way to take the measure of this lush and mountainous island, the smallest of the U.S. Virgins at nine miles long and five miles wide, and with a year-round population of 4,000. Jeep rentals are widely available, distances are short if circuitous, and many of the more than three dozen beaches and coves are reachable only by car. But if you take to the roads, keep a few things in mind:

* Figuring the amount of time to get from Point A to Point B is like remodeling your house -- triple the estimate.

* St. Johnians drive on the left -- the Virgins are the only U.S. possession where this is done. But, disconcertingly . . .

* . . . Their steering wheels are on the left, too. Locals will tell you that this is so drivers can see how close their cars are to the sheer drop-offs, or that it's easier to mail letters from the driver's side, or that it's convenient for talking to pedestrians in the middle of the roadway. You might notice that none of these reasons actually makes sense. However . . .

* . . . If you do come up behind someone who's talking to a friend in the middle of the roadway -- and you will -- do not honk your horn. That's just not how it's done here.

* Watch out for the dips, those out-of-nowhere, roller-coaster-like hollows that can send you airborne. At particularly risky spots, the government has thoughtfully posted bright yellow DIP signs. And some equally attentive islander has gone around and named them all, in carefully aligned press-on letters: Skinny DIP, DIP Stick, Big DIPper and so on. By the time you've negotiated Clam DIP, you feel like you're finally getting the hang of things.

Barreling around in a Jeep is fun, but St. John is really about one thing: snorkeling. Choosing a beach, however, can be stressful; there are 39, after all, each with something special to recommend it -- crowded, not crowded, sandy, rocky. . . Ask around for recommendations and the name that keeps popping up is Waterlemon Cay, but my first choice was the lesser-known Salt Pond Bay on the east end, billed as spacious, secluded and teeming with critters. (Correct on all counts.) Trunk Bay, on the north coast, was a little trickier. Widely considered the island's most beautiful beach -- it was the scene of the ill-fated Renee Zellweger-Kenny Chesney nuptials this summer -- it features a cool, self-guided underwater snorkeling trail, plus snack bars, snorkel rentals, showers, changing areas, gift shops and other amenities. All of which draw the cruise crowds -- not exactly a plus.

The secret: Arrive early. At 8:30 a.m. there was a grand total of five people on the palm-lined, sugary stretch of sand, and I was first in the water. It isn't exactly the Great Barrier Reef out there, but it was fun to check off the fish against the underwater plaques, and the coral looked surprisingly healthy for such a well-loved place. An hour later I looked up to find the bay bristling with hundreds of snorkels -- the Invasion of the Cruise People, right on schedule. It didn't seem to bother the fish.

If Trunk Bay is St. John's most photo-ready beach, little Gallows Point in Cruz Bay is the best surprise. I swam out to a floating dock looking in vain for Ralph, the resident stingray with whom everyone seemed to have bonded but me. I never did spot him, but no matter -- the parrotfish were out in force.

Later, flopped on the dock, I picked up investment tips from a fellow snorkeler, a Russian expat and self-made businessman who spent two years in a displaced persons camp after World War II, moved to Canada and now divides his time between St. John and Aspen. Moving on to the hotel pool, I chatted up another guest, a wedding planner and (she said) certified psychic. Two more exotic island attractions.

Back in Cruz Bay, we abandoned all thoughts of composting toilets and checked into the 60-room Gallows Point Resort, a lushly landscaped property whose two-story lofts and one-story garden suites overlook the harbor. Sipping my complimentary rum and Ting (it's an islands thing) on the tiled balcony, here's what I saw: green mountains dotted with red-roofed houses, blooming bougainvillea, wheeling seagulls, a marina bobbing with colorful sailboats and yachts. The guestbook featured breathless entries from honeymooners and families, with advice on snorkeling spots, restaurants and sunsets. A tip to live by: "Stay left and accelerate out of the turns."

Cruz Bay -- aka "Love City," a nod to the feel-good, live-and-let-live vibe that permeates the place -- has the requisite pastel storefronts, open-air eateries and palm-lined streets of most Caribbean capitals, with a sophisticated twist: more gourmet restaurants than you can shake a toque at. One night we feasted on lobster ravioli with pine nuts at a nouvelle Italian place called ZoZo's; another evening we hit the Lime Inn, beloved by locals for its fresh grilled lobster. And on our last afternoon, we lunched on a spicy mango gazpacho under a canopy of vines at Rhumb Lines, known for its Pacific Rim-inspired tropical cuisine and -- more infamously -- as the site of the Zellweger-Chesney wedding reception. Kenny, we hardly knew ye.

Our last night, we settled in to watch the sunset at the Jax Lounge, ZoZo's airy second-story bar. We had lots of company, with casual-chic couples lining up to pose in front of backlit clouds that were as stunning as the mountains. "Isn't that one of the prettiest pictures you've ever seen?" gushed a sunburned brunette with a North Carolina accent, handing her digital camera to the bartender. Pose. Click. Next!

Ritual over, we walked through the town, past lively bars and thumping discos, before turning onto our quiet little street -- and the dump trucks and other construction equipment that dwarfed our hotel. You don't have to be terribly observant to notice that growth is becoming an issue on St. John.

"It just breaks my heart that the island I love is changing so fast," said Pam Gaffin, a writer and tour guide who arrived from the States 10 years ago. Now she bemoans the trend of absentee ownership. "Fifty percent of our homes are owned by people who don't live here, and it's changing our community drastically. And all of these new condos are going to need water -- where is it going to come from?"

Guiltily, I asked what tourists could do to help. Keep visiting, she said. "Just don't buy a house here unless you're going to live here and be part of the community."

Most of the locals seem to have the usual love-hate relationship with tourists. Heck, many of them were tourists. Tiffany Milne, 25, a clerk at a Cruz Bay gift shop, said she visited from Maine six years ago, met her husband here and never left. "The first season I got here you could walk through town and see no one. Now there are a lot more year-round residents. It kind of sucks you in. I'll probably never leave."

I, on the other hand, had to.

K.C. Summers will be online to discuss this story Monday at 2 p.m. during the Travel section's regular weekly chat on www.washingtonpost.com. For a photo gallery with additional images of the Caribbean islands, go to www.washingtonpost.com/travel.

The view from a room at the Gallows Point Resort takes in the Cruz Bay harbor and surrounding mountains.St. John's Concordia Eco Tents are solar- and wind-powered.