MOTHER NATURE, though herself an abstraction, can be disarmingly tangible at times. One such time came in 1933 -- when, under cover of one of those old-fashioned nameless hurricanes, she saw fit to open up a wide trench from ocean to bay at about the midpoint of the barrier peninsula which then hugged the 70 miles of coast between Cape Henlopen, Delaware and Chincoteague, Virginia.

The blowout, which the city fathers of the adjacent small Maryland settlement of Ocean City soon decided was actually a pretty good idea, had two major consequences:

First, it abruptly increased the value of bayside property in Ocean City -- which helps explain why city fathers were so eager to name the new inlet, dredge it and flank it with protective jetties.

Second, and equally significant, it effectively separated what became known as Assateague Island from the burgeoning, seasonal, soon-to-be-a-major-motion-picture metropolis to the north.

As postwar development crept steadily northward (and eventually skyward) from this new Ocean City Inlet, plans also materialized to develop the Maryland portion of Assateague Island into resort housing. (In 1943, the federal government made a waterfowl-nesting refuge out of most of the island's Virginia portion.) Crews laid a central asphalt highway, and it was christened Baltimore Boulevard. Properties were subdivided and began selling, a few houses went up, funds were raised for a bridge from the mainland, and an elaborate lattice of "mosquito canals" was dug in the marshes along Sinepuxent Bay, to improve drainage and thus diminish the insect's bountiful standing-water breeding opportunities.

Most of the mosquito canals -- which didn't work, by the way -- are still there.

Most of the rest of the development, however, including Baltimore Boulevard and all but a few of the homes, was either buried or swept away by Mother Nature in March of 1962, this time in an infamous storm that remained nameless because it wasn't really a hurricane -- just a lethal coincidence of northeast winds, low pressure, heavy rain and a swollen spring tide.

This time, the would-be city fathers took the hint.

And as they backed off Assateague, the Interior Department, already itching for years to make the island the next major link in its growing chain of national seashore parks, moved in and started buying property.

Today, that unadorned, low-slung wilderness you see when you look south from your mid-rise condo or restaurant seat alongside the Ocean City Inlet is the Assateague Island National Seashore. Its slim, shifting length encompasses both the small, somewhat more hospitable Assateague State Park in the Maryland end and the much larger, wilder Chincoteague National Wildlife Refuge in the Virginia end.

If your opinion of a beach goes up as the honky-tonk hum of fortune wheels, quarter-a-shot arcades and roller-coaster romances fades, consider putting down your blanket and a cooler (no glass, please) on the other side of the Ocean City Inlet next time you're out here.

Assateague's guarded beaches are its most crowded, but even these account for less than 1,000 yards of a barrier island now about 37 miles long. About 15 of these miles are off-limits to four-wheel-drive vehicles, also; if it's alone you and your sweetheart (or sunscreen) want to be, you can pretty much achieve startling aloneness with a short walk. (Which helps explain why the more remote Virginia oceanfront areas were so popular with nudists -- until Accomack County outlawed public nakedness last summer, that is.)

The island is not for everyone, of course. Pesticides may be talked about out here in resource management land, but they're never used. There is only one food concession on Assateague, at the state park, and it's open only summers, only in daylight. The only island nightlife is the type involving either owls or the sort of foxes that hunt best on four legs.

From Assateague's white, windswept (especially since Hurricane Gloria's dune-stomping last fall) beaches on the east to the central thickets, flats and freshwater ponds and the loblolly pine forests and saltmarshes on the west live several hundred species of wild animal: probably best known are the squat, scruffy wild ponies, more than 200 of which roam the island freely.

Feeding the ponies is unlawful, of course. Feeding the mosquitos, on the other hand -- or the biting deer flies and blood-drawing greenhead flies -- is often unavoidable from May through October, except generally on the ocean beaches, where a consistent sea breeze keeps most of them away.

All in all, the island is an accurate representation of what the 30 or so miles of coastal peninsula north of the Ocean City Inlet used to look like, and -- if Mother Nature remains in the same unpredictable mood she's been in these last 100 billion years -- will look like again, eventually.

Half beautiful, that is. And half terrifying.

This could be a metaphor for life itself. But it also could be just the knee-jerk reaction of someone who was truly charmed by the view across Chincoteague Bay until someone else opened the car door and about 400 mosquitos flew in. ASSATEAGUE ACTIVITY

About 2.3 million people visited Assateague Island last year. On an average day in July, you'll find about 15,000 visitors on the island (compare this to the 250,000 daily summer average in Ocean City), two thirds of them at the Virginia end.

Most visitors arrive between June and September, as you might guess, and stay just for the day, on the beach, returning afterward to a hotel room or campground on the mainland, to the north in Ocean City or to the south on the separate island -- and namesake Virginia fishing village -- of Chincoteague.

The Maryland portion of Assateague, reached by the bridge carrying Route 611 over Sinepuxent Bay, offers about 300 yards of free guarded ocean beach, not including a smaller guarded area within the state park (which charges a day-use fee of $3); the Virginia portion, most of it a subtly protected, dike-crossed preserve at the eastern end of the Route 175 (about a 1 1/2-hour mainland drive south from Ocean City), offers about 400 yards of guarded ocean beaches.

*Camping. Some visitors to the Maryland end stay the night, either because they're patient, lucky, hardy, pennywise or crazy (though a combination of all these seems best). The National Park Service maintains some 125 primitive sites (cold-water showers, chemical privies, no hookups) in the Maryland end, on both the bay and ocean sides; about 300 less-primitive oceanside sites (hot-water showers in modern bathhouses, but still no hookups) are available in the state park, which accepts some campsite reservations -- unlike the National Park Service.

All the island campsites are, paradoxically, both hard to get used to (particularly after the insects arrive) and hard to come by (particularly after the summer tourists arrive). Most summer weekends, waiting lists are standard at both the state and federal campground offices.

*Surf fishing and hunting. Two principal areas -- along the ocean for about half the nearly 30-mile Maryland portion of the island, plus a small area at the island's southernmost hook in Virginia -- are open to four-wheel-drive vehicles with permits, mainly for surf fishing from spring through fall.

At times (including during the fall and winter hunting seasons for waterfowl, small game and deer in both states), you'll find a line of off-road vehicles waiting to get in -- especially in the Maryland end, which offers about 10 miles of oversand trails, from just south of the public beaches all the way to the Virginia line. (In the Maryland portion there's also a mid-island right-of-way, flanked by power lines, which doubles as an access road to the handful of private homes whose residents pre-date the Interior Department, and who retain rights to use the properties until various negotiated dates; the last retained-rights property is scheduled to revert to the Park Service in 2002.)

*Hiking and canoeing. The Park Service maintains five "back-country" campsite areas -- on both the bay and ocean -- for canoeists and hikers with permits and courage. These areas, particularly those among the flats and pine forests near the bay, are for campers truly into roughing it: You can only reach the camps on foot or by canoe. You supply everything but the picnic table, fire ring and lantern hook. In the summer months, this ought to include much insect repellent and a good working knowledge of, among many other things, poison ivy and hog-nosed snakes. The former is everywhere, and can be dangerous to those allergic. The latter are not dangerous at all -- there are no venomous snakes on the island -- but many are killed by campers and hikers who mistake them for copperheads, which they resemble.

*Birdwatching, bicycling, crabbing. All are possible in both the Virginia and Maryland segments of the park, but the wildlife refuge in Virginia boasts a significantly larger variety of bird life (and other wildlife), plus the more accessible and extensive network of bicycle and walking trails. The two best trails on the island, in fact, are contained in the wildlife preserve -- the Pony Trail, through bayberry stands, greenbrier thickets, pine forest and freshwater marsh to a winning view of the ponies silhouetted against Toms Cove; and the three-mile Wildlife Drive (somewhat misnamed since it's open to cars only from 3 p.m. to dark, before that to bikers and hikers only), which circles a large freshwater pond and pine forest dotted with egrets, swans -- and, on a recent visit, a solitary loon, and a solitary station wagon nearby with Maryland tags that read "LOON." HORSE SENSE

"Yellowstone has its bears," says Roger K. Rector, Assateague National Seashore's superintendent. "And we have our ponies. It's the same problem."

The problem, of course, is those of us who approach Assateague as if it were part of the Ripley's Believe It Or Not Museum across the inlet in Ocean City. We stop our cars, often abruptly, to ogle the ponies. We approach them; we may even feed them. They might be perfectly behaved.

Or they might bite or kick us -- a number of park visitors are sent to the hospital each year with such injuries -- possibly because they came to us expecting food but all they got was their picture taken, or their mane petted.

Come on. Name one other wild animal you'd want to pet.

Assateague's pony population comprises two distinct herds, separated by a fence at the state line. The Maryland herd, about 120 strong, is owned by the Park Service. The Virginia herd, somewhat larger, grazes the island by special permit and is actually owned by the Chincoteague Volunteer Fire Company -- whose "cowboys" perpetuate the tradition of rounding up the herd in July for an annual swim across Chincoteague Bay into town, where foals and yearlings are auctioned.

Legends trace the herd's beginnings to survivors of a 19th-century Spanish wreck. Recent research actually seems to support the theory, though the ponies carried by the ship were said to be substantially smaller. The present-day herd is thought to be the stocky, shaggy-haired, thick-skinned result of cross-breeding between the Spanish ponies and the livestock sent out to graze on the island in later years by mainland farmers hoping to avoid taxation.

Any pettable wild creatures come to mind yet? Assateague is home to quite a few other species, but most will do the sensible thing -- that is, attack or flee -- if you try to pet them. These include deer (both the native whitetail and the antelope-like Sika, imported from Asia by way of an ambitious Boy Scout troop in 1923), raccoons, muskrats, gray foxes, black snakes and the endangered fox squirrel. Birds found here, year-round and in migratory cycles, range from the ubiquitous laughing gulls and terns to the colder months' snow geese, blue heron and American egrets, to mute swans, horned owls, loons, sandpipers, cormorants, even an occasional osprey or peregrine falcon. CONTOURS

Over the next few years, the Park Service plans several low-key improvements to the roadway, bike trail and campgrounds -- mostly to ease peak traffic flow in Assateague, which is at or near its capacity most summer weekends (particularly at the public beaches and parking areas of the wildlife refuge).

"We're also looking at alternative ways of getting people out here without their cars," says Dennis Holland, manager of the federal refuge for the last five years and a vigorous champion of what he calls "realistic" development on the island -- though commercial interests in the town of Chincoteague sometimes prefer the word "unrealistic" applied to the same conservative policies.

Holland, however, a career U.S. Fish and Wildlife Service administrator whose father managed preserves for the agency's predecessor, need only point to an $80,000 segment of road installed south of the Virginia guarded beaches last fall -- and used for just six weeks before Hurricane Gloria erased most of it in a day.

"Anytime you build anything on a coastal barrier beach, one thing's for sure -- it's not going to be there for too long," says Holland. "It may be there 10 years, it may be 20 years, or 50, but, eventually, it's going to go."

Meantime, the Park Service and Wildlife Service do what they can to maintain a semblance of ecological balance on the island despite Recreational Man's considerable presence: roping off acres of beachgrass-covered dune to create protected nesting areas for the endangered piping plover, for instance, or cabling off a roadway through the inner-island flats, parts of which had been turned, by off-road overachievers, into barren, muddy fields of looping, twisting tire prints.

"In the summer we also have some of the best patrolmen in the world to keep people on the beaten paths," Holland says, grinning. "The mosquitos, the ticks, the poison ivy, the deer flies . . . they do a great job."

For some reason, you're not surprised to hear that Holland's favorite time on the island "starts in October, when the geese start arriving, and lasts through Christmas. There is nothing more beautiful than this place in the fall, and through the dead of winter. Now that's my personal season."

You could be pleasantly surprised, on the other hand, to walk along the ocean yourself -- from the Virginia public beaches north to Maryland, a seven-mile stretch closed to off-road vehicles -- and find, even in the crush and jam of summer, that you run into no more than a half dozen others.

Humans, that is.

On the other hand, if you squint while you leave highly temporary footprints in the hard sand closest to the sea, you will see plenty of double-crested cormorants diving for dinner beyond the breakers. Or a remarkable variety of stones and shells and smooth glass in the beach wrack following a storm. Or plover-like ruddy turnstones playing tag with the tide. Or unlucky horseshoe crabs -- beached, flipped over and eaten by gulls. Or even the occasional Goodyear whitewall, a distinctive seagoing creature which hails from an experimental Ocean City attempt not long ago to stem beach erosion with jetties made of tires.

For some reason, this will remind you of mosquito canals. ASSATEAGUE

AUTHORITIES ASSATEAGUE ISLAND NATIONAL SEASHORE -- Except for management of the refuge ocean beaches in Virginia, most National Park Service services are offered in the Maryland portion of the island, and they include 125 primitive, $5-a-night campgrounds (reservations are taken only for a limited number of group campgrounds; the others are available on a first-come, first-served basis, with a daily waiting list maintained throughout the summer); guarded ocean beaches (free) and bathhouses (about two miles south of the state park beaches); small-boat launching area; nature trail; daily and weekly naturalist talks and tours; back-country campsites for canoeists and hikers and a large information and exhibition center on the mainland. National Park Service, Route 2, Box 294, Berlin MD 21811. 301/641-1441.

ASSATEAGUE STATE PARK -- At the east end of the Route 611 bridge, the park operates 311 campsites ($10 a night to Marylanders, $11 otherwise), a protected beach ($3 a day), bathhouses and concession; and a bayside boat-launching facility. Administered by the Maryland Park Service. Route 2, Box 293, Berlin, MD 21811. 301/641-2120. CHINCOTEAGUE NATIONAL WILDLIFE REFUGE -- At the east end of the Route 175 bridge from Chincoteague, Virginia, the refuge has guarded ocean beaches (free and operated by the Park Service); extensive hiking, biking and nature trails; an information center and daily organized boat and bus tours, fishing cruises and walking tours. Noncommercial crabbing, clamming and surf fishing allowed in designated areas, as are four-wheel-drive vehicles with permits ($10 daily, $30 seasonal). Administered by the U.S. Fish and Wildlife Service. Box 62, Chincoteague VA 23336. 804/336-6122. OTHER SEASHORE PARKS CAPE HENLOPEN STATE PARK -- About 3,000 acres on the yawning lower jaw of the Delaware Bay, this popular Delaware park offers nearby Lewes and Rehoboth visitors a series of guarded ocean beaches; 159 campgrounds (water hookups only, modern bathhouses, no reservations, $10 a night); a nature trail and nature center; daily tours and talks; a fishing pier, Frisbee golf course, the old "walking dunes" and a new observation tower. Day-use fee for parking is $2 per Delaware vehicle ($4 per out-of-state vehicle, plus 50 cents for each occupant besides driver and one passenger). 42 Cape Henlopen Drive, Lewes DE 19958. 302/645-8983.

DELAWARE SEASHORE STATE PARK -- The five-mile stretch of relative wilderness between Dewey and Bethany beaches, with guarded beaches on both the bay and ocean side of Route 1, and close to 300 campsites ($10 to $14) just south of the Indian River Inlet, where the park also maintains a 250-slip marina. About half of the first-come, first-served campsites have three-point (water-sewer-electric) hookups; an additional 177 sites are open Thursdays through Sundays for self-contained campers only. Day-use fees are the same as Cape Henlopen. 850 Inlet, Rehoboth DE 19971. 302/227-2800.