When people think of Washington State, uch things as evergreen forests, rugged mountains, salmon and lots of water come to mind. Rarely, however, does the region conjure up visions of island-hopping, a pursuit more often associated with the Caribbean, Aegean or South Pacific.Yet the San Juan archipelago - a string of some 170 islets in northern Puget Sound near Seattle - has been providing endless recreational opportunities and vacationing pleasure to locals since the turn of the century.

Four of the larger islands - San Juan, Orcas, Lopez and Shaw - are served by Washington State Ferries, boarded on the mainland at Anacortes, 80 miles northwest of Seattle. Most visitors arrive on these large, modern ferries, bringing their cars, campers or bicycles to explore the islands' scenic and historic attractions.

Sailing is extremely popular in the sheltered waters of the San Juans and a growing number of Puget Sound charter operations are gearing up to serve island-bound boaties.

A word of advice about the ferries: during peak summer months (when locals traditionally swarm the islands), they're usually jammed to capacity (200 cars, 500 passengers), forcing long waiting lines for those boarding with vehicles. If your time is short or if you intend to stay put once you're there, you should fly to the islands.

San Juan Airlines operates a full daily schedule of commuter flights from Sea-Tac to San Juan and Orcas. If you're departing from downtown Seattle, an even better choice is Lake Union Air's floatplane service. Five flights daily originate at Lake Union in downtown Seattle, arriving in just 45 minutes at San Juan, Orcas or Lopez Islands. Most hotels and resorts operate shuttle services; there are taxis on San Juan Island and some combination of car, moped, bike or boat rentals on all four islands.

Your best strategy may be to avoid summer crowds, which not only clog the ferries but fill the islands' lodgings and campgrounds, by visiting the San Juans during the off-season - especially April and May or September and October. The weather is splendid (it's always warmer and drier than on the mainland) and islanders insist sailing, fishing and scuba diving are better in the off-season. During these delightful uncrowded times you'll find it much easier to get a room (most at lower rates) and to move around on the narrow roads. While they're normally quite friendly and hospitable, islanders seem even more so during the off-season.

For a first-time visit to the archipelago, I'd suggest a couple of days each on San Juan and Orcas Islands. Shaw and Lopez are largely unsettled and lack tourist facilities though they are ideal for cyclists, campers and naturalists who really want to get away from it all.

San Juan and Orcas, on the other hand, boast excellent accommodations ranging from luxury resorts to cozy B&Bs, good restaurants, plenty of shopping opportunities for ever-popular island art and handicrafts, plus numerous natural and historic attractions.

Bustling Friday Harbor on San Juan is the archipelago's largest community, county seat and major commercial center. It's a festive scene when the big ferries ease past rows of yachts and purse seiners to tie up at the wooden-pile dock and a procession of cars, trucks, campers, cyclists and pedestrians stream up the ramp onto Spring Street. Restaurants, shops, inns and taverns ring the picturesque harbor, offering the island's greatest variety of amenities.

Beyond the tumult of Friday Harbor, a blacktop road, flanked by pine forest and pasture, leads to Roche Harbor Resort. The antithesis of the pastoral ambience that dominates the island's interior and its distant points and bays, Roche Harbor is a laid-back and eminently fashionable resort community whose historic 1887 Hotel de Haro once served as a boarding house for lime quarry workers. The venerable old Victorian inn is flanked by a dockside restaurant, gardens, a swimming pool and tennis courts. Guests have a choice of bedding down in the ancient but well-preserved hotel or in spacious new condo units interspersed among the pines overlooking the bay.

Water sports abound and there's horseback riding and hiking trails galore _ but I found Roche Harbor Resort the perfect place to just kick back and relax and to enjoy the island's finest cuisine.

Dockside moorage is available for up to 200 boats and should you choose to fly to San Juan, Lake Union Air will deliver you right to Roche Harbor's seaplane dock.

History buffs will enjoy a visit to English Camp, just a few miles from the resort. Together with American Camp at the opposite end of the island, it forms San Juan Island National Historic Park. The old military post has been preserved in historic testimony to a 12-year joint occupation of the San Juans by the U.S. and Great Britain in the mid-1800s.

When an 1846 treaty left ownership of the San Juans in dispute, garrisons from both nations occupied San Juan Island. The English settled on the north end while the Americans took the south end. It was an uneasy, if not seriocomic division, that nearly broke out in conflict in 1859 when an American shot a British pig for rooting up his potato patch. Islanders refer to the incident as the "Pig War" though no shots were fired before land claims were eventually arbitrated in favor of the United States.

Both camps feature restored period buildings, giving visitors a feel for life on the islands in the mid-19th century.

Nature lovers will want to visit Whale Watching Park on the west side. It's the only park in the nation created specifically to observe the magnificent orcas (killer whales) which regularly pass the waterside park. Several large pods, numbering about 80 whales, frequent the San Juans, as do migrating minke and gray whales.

You can learn more about cetaceans at the Whale Museum in Friday Harbor. It evolved from the offices and laboratories of a research organization and features a number of scientific and artistic exhibits illustrating the natural history of whales. Museum naturalists accompany wildlife cruises aboard the 46-foot Western Prince and these experts will dazzle you as they identify orcas by name.

Don't forget to look skyward now and then. The San Juan Islands are home to one of the largest colonies of breeding bald eagles in the continental United States.

Drive, bike or hike to the summit of Mt. Constitution and you'll be rewarded with one of the world's most amazing views. On a clear day you'll see not only the entire archipelago but the Olympic Mountains in the south, the Cascades in the east and the Canadian gulf islands and Vancouver in the west and south.

Eastsound is Orcas' main settlement and its Victorian inns and storefronts and weathered redwood salt boxes evoke a scene reminiscent of the Maine or Massachusetts coast. It is a village of excellent restaurants (Christina's is the best), boutiques and galleries that feature the works of Orcas' large community of artists. Creativity blooms as abundantly as the berries and wildflowers on Orcas. On a timberland road three miles southwest of Eastsound is Orcas Island Pottery, one of the most highly regarded ceramics studios in the Northwest. Near Olga, just south of Moran State Park, Orcas Island Artworks is a co-op gallery featuring a large display of quality work from local artists and craftsmen.

After a busy day of sightseeing, shopping, hiking or biking, pamper yourself with a stay at Rosario Resort and Spa. Built in 1904 as a retirement retreat by Seattle shipbuilding magnate Robert Moran, this sprawling seaside estate has as its focal point a 54-room, five-story Mediterranean-style mansion built to nautical specifications by Moran's own shipwrights. Finished in mahogany and teak and fitted with brass railings and fixtures throughout, it resembles the interior of the most elegant cruise ship.

Centerpiece of the great house is its huge mahogany-paneled Music Room on the second floor, complete with a two-story Aeolian organ sporting 1,972 pipes. Highlight of any visit to Rosario remains the 5 p.m. organ concerts Wednesday through Sunday by Christopher Peacock, the resort's public relations manager and resident historian who, dressed in black tie, intersperses his musical performance with anecdotes and a slide show tracing Rosario's colorful history.

In the basement, with its elaborate Italian mosaic tile floors and Romanesque arches, Moran built a game room and an indoor swimming pool. The pool, one of three at the resort, is still in use along with a more recently installed sauna, whirlpool and fully equipped gym. Guests can still sign up for fitness classes, massages, exotic body wraps and facials.

New chef William Jung, formerly at Florida's fabled Boca Raton Club and the Boulders in Arizona, has completely revamped the Orcas Room menu, adding a number of delectable local seafood dishes and a special menu aimed at calorie-conscious spa-goers.

Rosario's 179 guest rooms and suites are scattered beside the mansion and along a bluff with a sweeping view of the bay where the resort maintains a private marina. Just as it does at Roche Harbor, Lake Union Air services Rosario with daily floatplane flights to and from Seattle.

History has it that when Robert Moran, at age 49, began construction of Rosario he was extremely ill with heart trouble, a nerve disorder and stress. His doctors had given him but six months to live. Thanks, apparently to the salubrious effects of Orcas living, Moran stretched his six months to 37 years.

In fact, he outlived most of his relatives. So he deeded Mt. Constitution and nearly 5,000 surrounding acres to his fellow citizens _ to become, as you've probably guessed _ Moran State Park.

While there's no guarantee that a San Juan Island vacation will add years to your life, it surely will provide a refreshing and restful respite from your daily routine.

For more information, contact:

San Juan Island Tourism Co-Operative, P.O Box 65, Lopez Island, WA 98261. (206) 468-3663.

Washington Tourism Development Division, 101 General Administration Building, Olympia, WA 98504. (206) 586-2088.

For a free copy of the Washington State travel planning guide, "Destination Washington," call toll-free (800) 544-1800.

* Dave G. Houser lives in Malibu, Calif.