SMITH ISLAND IS not a tourist trap.

People looking for life in the fast lane, or at least a roller coaster of happenings are advised to go elsewhere. On the other hand, life on Smith Island, Md., in the middle of the Chesapeake Bay is not without excitement.

Almost any evening, big old American cars sans mufflers and tags rumble back and forth along the 1 1/2-mile "highway" connecting the towns of Ewell and Rhodes Point. American Graffiti with rust.

The Island Gift Shop is the stationary teen-agers' hangout, complete with two pool tables and half a dozen video games. Even Space Invaders has invaded Smith Island.

For local color, there's the back of LeRoy Evans' general store, where grizzled watermen talk about the weather and the water in an 18th-century English dialect you won't understand--and watch the network news on a color TV.

Smith Island is a lot like everywhere else, except different.

Accessible only by boat, it lies 11 miles east of Crisfield, the crab and oyster capital on Maryland's Eastern Shore. It has three towns with approximately 650 inhabitants--a third of them named Evans, with Marshalls, Tylers and Bradshaws close behind. There are four Elmer Evans--Elmer L., Elmer F., Elmer W. and Elmer W. Jr., who is universally known as "Junior Evans."

Despite the confluence of clans, Smith Island is not always one big happy family. Like everywhere else, there are factions and feuds. Ewell is where the money is, Rhodes Pointers tend to resent Ewell's prominence and Tylerton, the third town, is accessible from the other two only by boat. It is said they speak an older, older English over there.

Although it is part of Somerset County and the State of Maryland, Smith Island has been a world apart since its settlement in 1657 by religious refugees from St. Mary's City and Jamestown.

It is a place without street names. In Ewell, you're either "over the hill" (which refers to a barely discernible incline on the low-lying island) or "down the field," referring to the other landmark which doubles as a baseball diamond and the site of an annual tent revival each August.

There is no island government, no mayor, no town hall, no police force. There is instead the United Methodist Church, to which all islanders subscribe. With funds raised through the council of ministries from the three small congregations, the church pays for the street lights and the clinic.

Smith Island has no doctor, although the preacher periodically proclaims its need for one to the outside world. Lately, a succession of metropolitan medicine men have been doctoring on weekends in return for lodging. To them, it's an escape from medical economics. The payoff is intangible.

Frances Kitching, who serves meals to mainlanders in her living room and boards them upstairs, explains it this way: "It's a different place, which they are expecting that. They say, 'Where can I go?' I say anywhere you like. There's no tourist attraction."

The tourists come anyway. They come by sailboat, anchoring in the channel which is really the main street of Ewell. Some are Chesapeake voyagers, others are en route to or from Florida, making their obligatory Smith Island stop on the inland waterway.

Some day-trippers arrive aboard the "Captain Tyler," a tour boat that leaves from Somers Cove Marina in Crisfield and takes them to Alan and Dixie Tylers' Bayside Inn in Rhodes Point for family-style food and a 25-minute island tour in a bus driven by Betty Jo Tyler, their 18-year old daughter.

Still others board Frank Dize's Island Belle II (which is also the mailboat) or the Jason I or Jason II, named after co-owner Clarence Tyler's son. These are the boats the islanders themselves ride, on their occasional trips to the doctors and the shops of the Eastern Shore.

A third boat owned by Clarence Tyler and Glen Marshall takes people to and from the Chesapeake Bay Foundation's house on Tylerton. Alan Tyler owns the school boat, named after his daughter, which daily takes 42 Smith Islanders to and from Crisfield for high school. Wade Tyler, Alan's son, operates it.

None of these boats ferry cars. Islanders pay $35 to barge their vintage clunkers over to Smith. Tourists are advised to leave their automobiles on the mainland, near the Crisfield city dock. The overnight parking fee is $2.

The 40-minute boat ride from Crisfield to Ewell is a trip across time as well as space. Elizabethan accents are audible, barely, above the drone of the vessel's engine. My first trip, on a windy, rainy January day, was wet and wild, the bow pitching up and down to meet the whitecaps. Normally, it is possible to position oneself in the open stern section, and there enjoy the breeze with only occasional spray.

On a crystal clear day, the thin treeline of the island is almost visible from the water just outside Crisfield. But on the Chesapeake, the shortest distance between two points is rarely a straight line, water depths being what they are. To the uninitiated, the circuitous channel into Ewell seems endless but it also acts as a transition: Either side is marsh for miles, with hardly a house or tree in sight.

The boat stops first at LeRoy Evans' dock. Charley Evans, his son, unloads boxes of dry goods and other foodstuffs from the mainland. Then, it proceeds to the passenger wharf, before ending its voyage in Tylerton. The first dockside view is often of crab pots, rectangular-shaped wire mesh structures stacked all over the place, and oyster shells.

Once on the island, tourists eventually eat. Seafood, of course. Needless to say, it is fresh, although, for the record, it should be noted that most Smith Island watermen sell their crabs and oysters to the Crisfield packing houses and some even ship their catch to New York's Fulton Fish Market.

Among Smith Island aficionados, Frances Kitching's cooking is widely known. It is very good. It is also ample. If you turn down seconds, she'll want to know why: "If you like it, tell your friends; if you don't, tell me."

On several visits to the island, my dinner companions at Frances Kitchings' have ranged from telephone linemen to Topsider-sporting yachters. Always present and appreciative of his wife's food is Ernest Kitching, a retired watermen who keeps his hand in mending crab scraping nets.

At one end of Ewell sits Pitchcroft, an 18th-century farmhouse now operated by Eloise Tyler as a restaurant, with four bedrooms to rent. Also in Ewell, Bernice Guy rents two rooms and uses a spare bedroom in her sister-in-law's house next store for the overflow. She also cooks meals.

The innkeepers of Ewell all charge $28 per person for room and two meals, with half-price reductions for children. Over at Rhodes Point, the day trip, tour and meal at the Bayside Inn costs $20, $10 for kids under 12.

Before or after eating, to tell the truth, there isn't much to do. That in itself is a novelty for most people. One pastime is walking. Years ago, before the churning Chesapeake cut a channel through the marsh, you could walk to Tylerton, but not now.

Nonetheless, there are 5 miles of narrow lanes and one main road--which is sometimes under water at high tide--linking Ewell and Rhodes Point on Smith Island. Until a few years ago, the road to Rhodes Point was paved with oyster shells. Then, the government put in a new sewage treatment plant and, after laying the pipes, covered them and the shells with tar. The tar turns gooey during hot summer days, which the islanders view as one more example of mainlanders messing up their world.

The worst tar horror story concerns Olivia Tyler, known as "Miss Levi," who, at age 92 a couple of years ago, got stuck in the stuff crossing from her home to her general store in Rhodes Point. (She still operates it a few hours a day, theoretically in competition with her son, Clinton, who has his own store down the road.) They say they had to lift her from her shoes. Family pets have fared worse.

The tar is tracked everywhere. Summertime cloggers, beware.

The road to Rhodes Point passes the island dump, on your left. Here, you may see discarded beer bottles, testimony to the fact that although there are no bars on Smith Island, some residents have been known to swig a few now and then. The dump, islanders admit, is an eyesore. But it serves a purpose.

Past the sewage treatment plant, a compact modern building halfway to Rhodes Point, sits the island's auto junkyard. Once a mountain of rust, it has been reduced to a small hill since publicity over the problem attracted a private contractor who sold some for scrap. An Army promise to remove the rest last year has not been fulfilled.

Still, Smith Island is scenic. The houses are mostly white-frame turn-of-the-century dwellings. There's a mountain of oyster shells to behold in front of the small shucking house in Rhodes Point, which also has a marine railway. Half-sunken work boats rest on shallow bay bottom.

My favorite time on Smith Island is early morning, when the work boats chug out of the channel from Ewell in the predawn darkness, a flotilla of fishermen following the water as they have here for generations. Sunrise in this setting is almost worth keeping watermen's hours.

Just about anytime, the marshscape is a stunning sight and the road to Rhodes Point is as good a place as any to view it from land. Birds punctuate the Chesapeake sky. In the distance, Tylerton can be seen, and beyond lies the Bay itself, which feeds the islanders even as its wind-whipped waters eat away at the island. Southwesters and northeasters do the most damage.

Erosion has erased other island communities of the Chesapeake, and it is much on the mind of Smith Islanders. Rhodes Point is especially threatened, and, although the Army Corps of Engineers has studied the problem, nobody seems to have the money to build the bulkheads and jetties needed to save the island. So, enjoy it while it's there.

You may be a stranger to the world of Smith Island, but be forewarned that many of the islanders know all about yours. Their television reception is good, and some have spent time working on Washington's southwest waterfront or in other city settings, almost always to return.

Still others have turned tourist themselves. The other week, a group of 30 senior citizens took a mainland bus trip to Baltimore's Harborplace. According to Dixie Tyler, Miss Levi, who just turned 95, was the first one to sign up.

Frances Kitching has also been to the acclaimed inner harbor, with its science center, aquarium, paddle boats and other things to do. She was there this spring to promote, "Mrs. Kitching's Smith Island Cookbook," and she formed an opinion about Maryland's newest and biggest tourist attraction.

"I think it's overrated," she said.