You start to notice the little things as soon as you arrive in the San Juan Islands, the exquisite archipelago that floats between Washington state and Canada's Vancouver Island, at the northwest corner of the contiguous United States. In fact, your perceptions become more finely tuned even in the approach to the islands.

The San Juans are so closely clustered, you could shoot an arrow between many of them. But they show striking differences of terrain, character, recreational opportunities and even climate: There is an unending variety of choices here for the traveler. Thanks to the "rain shadow" of the Olympic Mountains, for example, southern Lopez Island gets under 20 inches of rain a year but northern Orcas gets about 40.

You can't drive to these islands; last year, when the Washington Department of Transportation revived the notion of building bridges to and between the various San Juans, it was quickly hooted down by islanders and other island-lovers. We may curse the delay, inconvenience and expense of transport to waterlocked islands, but we know these are the small prices of isolation, and that isolation is part of what makes islands different from all other, more humdrum places on this globe.

Nearly all residents and visitors alike get to the San Juans via the state ferries, which chug between Anacortes and various islands 16 times a day in summer and seven in the off season.

The ferries themselves are drab as Greyhound buses, but a laminated plastic booth or metal guard rail is all the seat you need to enjoy the passing spectacle: a lovely labyrinth of marine "passes" guarded by isles that range from humble boulders to fir-shrouded mountains. The cruise of 45 minutes to two hours (depending on which island you debark at -- stops are made at from one to four of the San Juans, and at Victoria on Vancouver) does wonders to soothe city-frazzled spirits and inculcate the easygoing outlook evoked in the local expression "island time." A sense of island time makes it easier to beat the frequent delays in ferry service.

The San Juans aren't a big place: At 179 square miles, they constitute the smallest county in Washington in area, and, with 8,700 people (increasing to nearly 14,000 during the summer tourist season), one of the smallest in population. But packed into them is enough variety of scenery and sensory delight for an entire state.

Begin your appreciation with a bird's-eye view: Leave the ferry at Orcas Island, the second-largest of the San Juans, and cross the island -- you can bring your bike, moped or car on the boat or pick up one of the limited number of rental vehicles at your destination -- through the picturesque village of Eastsound and the popular lakeside campgrounds of Moran State Park to Mount Constitution.

In true San Juans fashion, Mount Constitution doesn't measure out to much of a peak -- it's less than half a mile high. But it's a giant in its setting, and hence affords what's been described, not unreasonably, as simply "the best view in the world."

In the distance on three sides loom the snowy peaks of the Cascade Mountains, the Olympic Mountains, Vancouver Island and, if the air is clear, the giant volcanic cones of Mounts Baker and Rainier. To the west is open ocean. Freighters and ferries in the distance dot the glittering lacework of straits and fiords. Far off -- more in sensibility than in miles -- rises the smoke of Seattle, Vancouver and the other ports of the island sea. And all around is a mosaic of green islands, spreading nearly as wide and as numerous as clouds viewed from a jetliner.

The official count of islands in the San Juans chain is 172, but the tally can mount to four times that, depending on where you draw the line between a rock and an island and whether you count when the tide is in or out. As you'd expect, such a biosphere supports a rich lode of wildlife, whose survival is aided by the designation of 84 islands as a national wilderness (land that is set aside by the federal government and remains untouched by man) or a wildlife refuge (an area selected as a wildlife habitat and manipulated for that purpose). Seabirds, seals, river otters and foxes are common -- deer so much so that local gardeners curse their bold foraging -- and the San Juans host the largest and healthiest colony of bald eagles in the Lower 48.

But the biggest thrill, I'm told, is to spot one of the three pods of orcas (killer whales) that ply the local waters. These once-feared master marine predators are on their way to becoming a major tourist attraction -- and, like other attractions, suffering from all the attention. San Juan Island has a fascinating Whale Museum, stocked with skeletons and all manner of lore, and the first official "whale-watching park." Even larger gray whales and smaller minke and pilot whales and porpoises also cruise the chilly straits.

In the San Juans, humans have reversed evolution and followed the whales back into the sea. As long as people have inhabited the islands, they've fished their rich waters. Some still sustain the ancient, simple art of reef-netting, amidst a new wave of experiments in fish, oyster and seaweed aquaculture. Most year-round residents, however, are either retired or earn their living from tourism. Sports fishermen and Sunday clammers throng to the islands' natural trove, though oldtimers here as everywhere lament its gradual depletion.

The San Juans are the favorite mecca in the Northwest for sailors and sea kayakers; their secluded coves and inlets offer a virtually unlimited choice of sites to explore. A whole generation of backpackers seems to have discovered how much more relaxing it is to paddle your gear into the wilds than to haul it up the slopes. You can rent all manner of paddling and sailing gear at Friday Harbor and other island ports, but if you're just starting at kayaking, it's wise to take instruction from a seasoned guide. Paddling is not only delightful but deceptively easy when the sky's clear and the water glassy, but the tides and weather hereabouts are notoriously treacherous.

Kayakers haven't yet created traffic jams here, but the bicyclists do in summer: The islands' twisting, always scenic roads and low speed limits seem ready-made for pedaling. You can rent bikes on Orcas, Lopez and San Juan islands, and mopeds on San Juan. Orcas has the steepest hills, and Lopez the fewest.

Orcas has not only the most hills and forests but the most resorts. They range from the Northwest's largest, the opulent but (except for its grand old centerpiece mansion) somewhat sterile Rosario (206-376-2222), to the amiably "new-age" Doe Bay Village Resort and Retreat Center (206-376-2291), which has the cheapest and funkiest accommodations and the best sauna around. Rosario's condo rentals range from $79 a night double (two additional guests can stay for $7 each), to $160 for a suite that sleeps six; rates at Doe Bay, which offers hostel-like bunks and cabins, run from $17 to $47.50 double.

Lopez Island is just the opposite in most ways: the most serene of the three major islands, still more rural than recreational, though like the others it has several good restaurants and bed-and-breakfast facilities -- plus one resort, the Islander, done up in droll South Seas thatch and carved idols. Its rolling green meadows, dotted with weathered barns and odd wooden water towers, may leave you thinking you took a wrong turn and landed in Wisconsin. The Lopez sheep and cows are famous for their fence-running escapades, which are often the high point of the local police blotter.

San Juan, the largest island, has elements of the others' terrain, plus windswept beach cliffs straight off a Monterey post card. It also has the nearest thing to a real town -- Friday Harbor -- the biggest marina, the most acclaimed restaurant (the Duck Shop Inn), a first-class summer jazz festival and a stately old gingerbread, ramshackle resort, Roche Harbor (206-378-2155, rates from $40-$75 double).

Shaw, the fourth island the ferries stop at, offers little except peace, camping and what is probably the only ferry dock in the world run by nuns wearing habits -- members of a Franciscan convent who work as agents for the state ferry system. You needn't disembark to enjoy this unlikely sight.

The sociology of the islands is as rich and diverse as their geography. Many scions hang on from the days when the San Juans were a backwater haven of farmers, fishermen and smugglers. But they've been joined by the usual summer-home set and a wave of latter-day rebels and romantics drawn to what one paradigm of that generation, politician and insurance broker Jim Klauder, calls simply "the most beautiful place on earth."

Their watery moat insulates the San Juans from the trendiest excesses of the "paradise syndrome." Nevertheless, they feel the pressure: In the 1970s, their population doubled. San Juan County became the fastest-growing county in the state, though -- because of a limited employment base and the hurdles to dispensing services to scattered islands -- it was perhaps the one least prepared to handle growth.

Klauder finally left to run for Congress on the mainland, after taking hard knocks as the county commissioner who spearheaded the passage of a controversial comprehensive land-use plan. Others who stay may wind up shelving their degrees and pumping gas or waiting tables; like all paradises, the San Juans are a better place for the independently wealthy and independently poor than for those who have to make a living. Some find only a bitter empty pot at the end of the rainbow. But almost all become passionately attached to the land and waters they've made home.

And there the fight begins. Tempests in a teapot are a long and glorious tradition on the San Juans, ever since the glorious Pig War of 1859. The United States and Britain had forgotten to include the islands in their 1846 division of the Northwest. So they settled them jointly, and peaceably enough, until a Mr. Cutler of the Hudson's Bay Company shot a pig belonging to an American (a Mr. Griffin) that was rooting in Cutler's garden. Griffin demanded $100 restitution; each appealed to his government for protection. The two powers rattled sabers and stationed garrisons on San Juan Island until 1859, when Kaiser Wilhelm of Germany was called in to arbitrate.

The United States got the San Juans, and Britain the remainder of the archipelago to the northwest -- the wilder, quieter and equally beautiful Gulf Islands. (Don't call them "the Canadian San Juans" around the locals.) The old American and English camps on San Juan Island are now a national historical monument.

Today the land-use disputes have broadened beyond pigs and gardens to a running battle over the very future of the islands. Fighting over how much to develop, or how zealously to preserve, the San Juans is a favorite indoor sport, played with recall elections, partisan periodicals and an endless round of threatened and actual lawsuits. Political discourse is raised to an internecine fervor perhaps not seen since the days of Webster and Calhoun.

Where but in the San Juans would bald eagles become a point of furious contention? Tree-cutting and development are curtailed near their nests, and some patriotic types invoke "the American way" in inveighing against such regulation to protect America's mascot.

But if you're not on the wrong end of a development dispute, the islanders can still be the most friendly, good-humored and charming people you'll ever meet. You get an inkling when you land on Lopez and notice that everybody waves at everyone else -- not flashily, just a brief lifting of a few fingers from the steering wheel as you pass. Wave too broadly or not at all and you're branded as a tourist.

What the old prospector said in the movie "Butch Cassidy and the Sundance Kid" translates well to the islands: "You spend too much time in Bolivia, you get colorful." Folks here show a knack for telling yarns about everyone who lives close to the sea and wind. Listen for them in any shop, or best of all in Friday Harbor's dockside fisherman's bar, the Mariner. Like the one (true) about a fisherman named Jake at a noisy boat party who craved a little shuteye. He grabbed his flotation suit and a fifth of vodka, jumped overboard and floated blissfully till morn around Fisherman's Bay. When a deputy fished out the apparent drowning victim, then tried to nail him for public drunkenness, he just swam back to sea.

Quirky as they are, the San Juans are not a foreign country. But they may be the only place in the nation from which you'll have to clear customs to enter the rest of the United States -- should you chance to board one of the ferries that start out in Sydney, on British Columbia's Vancouver Island, and doesn't make official entry until Anacortes. A few tourists are regularly thrown into a panic or fury at the unexpected imposition.

Forewarning of a few other local peculiarities can save you even larger anguish. Leave your dog on the mainland, or make sure you keep him leashed. Livestock kills by pet pooches are a perennial problem, and a sign at the Friday Harbor ferry dock warns that trespassing dogs may be shot. Leave your car behind too, or prepare for lines and delays that, on a sunny summer weekend, may strand you all day. Bicycles and motorcycles not only ride much more cheaply but scoot to the front of the line, to the chagrin of car drivers. If you must drive, don't tank up on Orcas. There, thanks to mysterious vagaries of distribution, gas costs as much as 40 cents more than on the other islands. Reservations -- for both accommodations and rental vehicles -- are advisable, though not always necessary, in summer, when even the campgrounds fill up.

Such minor pitfalls only remind you you're in a very different kind of place. Islanders treasure that difference: One of their worst epithets is "off-islander." They even gloat over the differences between their near-flung islands.

I sat one Saturday night in the Islander bar on Lopez, while a talented band from San Juan Island rocked the place to its thatched rafters. At the end of the first set, a burly Lopezian named Howard Wixon hollered out, "Not bad for off-islanders!"