LIKE EVEREST, but far more accessible, the beach "is there." For better or worse, millions seek it out today as some have for ages. Indians who wintered inland spent their summers on these shores, though Europeans didn't discover the delights of warm-weather beaches until the 18th century. The early colonists, of course, settled the coasts for practical reasons; few gamboled on the strands before barging west with a "Bible and jug in one hand and (like as not) a native tomahawk in the other," as Faulkner put it. Americans didn't start going to the beach in playful earnest until the 1850s, when a group of New Jersey boosters persuaded a railroad to serve Absecon Island. Thus Atlantic City was born. It came of age in 1870 with its first boardwalk, which was built because hotels complained about guests tracking sand in from beach. An ominous beginning. Now Orrin Pilkey Sr. and Jr., primary authors of the well-regarded How to Live with an Island warn about "the New Jerseyization" of the coast as fat south as the Carolinas. Somehow the motive behind the first New Jersey boardwalk and the latest seaside condominium recalls a famous fictional pair:

The Walrus and the Carpenter

Were walking close at hand.

They wept like anything to see

Such quantities of sand:

"If this were only cleared away."

They said, "it would be grand!"

"If seven maids with seven mops

Swept it for half a year,

Do you suppose," the Walrus said, "That they could get it clear?"

"I doubt it," said the Carpenter,

And shed a bitter tear.

I find myself on the oysters' side. The beach is better off without people who dislike it as it is. May some beaches be saved from sweepers, carpenters, builders of boardwalks, and others who would change it into a different place. When I want all the comforts of home, I stay there. When I want a sense of the real world, an adventurous rest or just a thorough airing, it's beach time.

Why go to the beach? To see the critters, to taste the rose hips, to let a child reinvent castles in the sand, to find a whale's jawbone. For isolation and the challenge of elemental living. For superb sea-fresh food simply cooked outside or in a cottage kitchen. For a lover's constant quiet company. For the contrasts of a sweating run and then a surf swim; of a freezing day-long walk, then hot chowder. For the slow, sensuous roller coaster of searing noons and sleep in salty air. For the certain fury of a gale, the glory of the burning sun's rise out of a calm sea, for the miracle of diving birds and the rare wonder of walking naked in moonlight. For the itch of sand between the toes and glimpses of infinity . . .

THE BEACH, like Rhett Butler, frankly doesn't give a damn. It doesn't care whether folks visit or not, even whether a visitor lives or not. This is not to say that the beach maliciously deadly. It is impersonal, remote (and in another sense, the remoter the better). Since wild beaches lack telephones and First Aiders behind every dune, people visiting them are on their own and had better know what they're doing.

Anyone going beyond the boundaries of a "protected" beach must be alert to the kinds of pitfalls that can appear. Of course it's best to avoid physical problems, but once encountered they must be addressed directly and on their own terms; you can't con a wave.

Urban sophisticates are adept at resolving all sorts of difficulties verbally, like talking cops out of traffic tickets. But the sun's ultraviolet rays have no interest in extinuating circumstances. They just burn, and seem to burn hotter in spring than autumn, though that appearance is misleading.It's a matter of one's having gotten used to sunshine. By the same token, because the body's temperature-control mechanisms function best after steady use, a winter's layoff means that sweat glands simply don't work as well in the first week of summer as they will after Labor Day. Even fatigue is a matter of conditioning - not of one's imagination or moral laxness. The beach is a physical place and can be dealt with only in physical terms. The problems it presents cannot be disarmed by personal charm or pleas for sympathy: A Portuguese man-of-war has no ears.

BORN AND RAISED on Cape Cod, Richard T. Baker has guarded lives on beaches facing at least three oceans. He is presently hatching plans to elevate lifeguarding from an informal part-time business of whistle-blowing and macho showmanship to a nationally recognized profession that involves tested standards and universal principles. Very strong and almost pathologically fit, Baker stays that way by respecting the powers of the sea. During ten years at Assateague National Seashore, where he is chief lifeguard, he has seen arms broken, thighs fractured, vertebrae cracked, and both shoulders dislcated in people who were "just dumped by a wave." His first rule when entering the surf is simple: Don't do it yet. Wait a minute - wait five - and watch what's going on. With a little practice and experience, simple observation can show you a great deal about the water and the surface of the shallow ocean bottom.

First, estimate the height of the breakers and, hence, their power. There's no need to compute foot-pounds of force; just visualize the strength of their impact if one should break over you at shoulder height - or catch your child across the knees. Anticipate just how far out you (and others with you) can safely wade or swim.

Next, look for currents and underwater sandbars. That sounds as if it requires clairvoyance or X-ray vision, but in fact it's easy. Because of the physics involved, waves steepen dramatically when the water they pass through gets shallow. Obviously, waves break in the surf zone near the beach. Breaking waves are the ones to watch out for, because they physically transport water and whatever's in it - including people.

Look farther out as well; there's usually another line of cresting waves, betraying an underwater sandbar, a fairly abrupt shallowing. That line of cresting waves, which keeps appearing at the same place, indicates the shape and extent of the bar, which lies roughly parallel to the beach. Since bars mean shallows, the water there may not be over your head; often a bar offers a place to stand and rest.

Whether the tide is rising or falling, the water breaking on her the tide is rising or falling, the water breaking on the beach must go somewhere; it seeks it own level in the sea, rushing away from the land to create a mythological "undertow." Call it "backwash." Certainly this rush of water can nudge a wader's feet out from under him, especially at certain tide phases on the steepest slope of a summer beach. If that happens and the wader falls down, more backwash tumbles him farther downhill. Folks promote this simple phenomenon into the fiction of a malevolent force bent on dragging them the breadth of the continental shelf. It's simply the flow of water going its own way when new waves arrive. Farther out is where things can get really perilous.

As waves cross a sandbar they can create discrete inshore currents, occasionally alarmingly strong. Flowing between the surf and the sandbar, these currents are sometimes dangerous, especially to unsuspecting swimmers. They are strongest where they break back out through a bar, since openings in the bar act like funnels. The currents move seaward surprisingly fast, especially in relation to the nearby land-bound waves. Misnamed "rip tides," the most dramatic and disarming of these currents occur when they run perpendicular from the beach, heading straight out to sea. This is a rare, says Baker, but when it happens the results can be terrifying.An unwary swimmer paddles happily on an oblique line toward the surf, then finds himself suddenly being swept away from shore. The swimmer panics, understandably, and tries to make shore via the shortest route: i.e., by turning right around and swimming straight back. The result can be swift exhaustion and possible drowning, since few organisms besides fish swim faster than these currents.

By observing where lines of breakers end, one can anticipate the location and direction of these currents. A sharp break in a surf line parallel to the beach means that's where a rip current passes seaward through the bar. It has scoured out a deeper channel in the underwater sand, so incoming waves don't crest or break the way they do above the intact sandbar.

Rule One: Stay away from such currents by staying away from gaps in lines of breakers. They are rarely more than several yards across and they are widely spaced. Swim somewhere else, within unbroken sandbar.

Break Rule One and your life can depend on assiduously observing Rule Two: When you get caught in a rip current, don't fight it head-on because you'll probably lose. Stop. Tread water. Get your bearings. Then move at right angles to the current: Swim across it (even though it's still carrying you seaward) until you're outside its influence. This will take only a few strokes, since these currents are narrow. Alternatively, if you passively let it carry you past the bar, you'll find that a rip current dissipates beyond the line of cresting waves. Then drift into the crest line and let the breaking waves push you back toward shore; use the ocean's energy to your advantage.

Instructions like these are easy enough to codify in my comfortable study on a quiet night in Washington, when most locals are away and even the tourists have taken their groaning Winnebagos off to bed. It's an entirely different matter on a windy day in brisk surf 30 yards from an East Coast beach that threatens to vanish over the western horizon. Please remember anyway: Don't panic. Turn right or left 90 degrees and swim across the current to slower water that's moving the righgt way. And if you do get into trouble in sight of people on shore, don't try to wave both arms violently to attract attention. That just wastes energy and makes you sink besides. Tread water and raise one hand; it'll be obvious that something's amiss - should anyone be willing and able to help in time.

Rip currents running straight away from land are rare. Currents running obliquely through a surf zone are more common. They're more insidious too: More subtle and longer, they move away from the land less dramatically. But the same rules apply. If you see a surf line slanting away from shore, recognize that a current probably goes the same direction. Avoid it. If you forget and it starts carrying you the wrong way, don't try to swim against it. Swim across the current to easier water before heading back to the beach.

Closer in, when you start playing in the water, notice which way you're being carried. The surf pushes everything a little distance alone the beach with each wave. Almost every working day, Baker sees a parent bawl out some innocent kid: "Didn't I tell you to swim right there ?" It's an impossible order to obey. The slight slant of the surf will always carry a swimmer or wader up or down the beach. It takes a conscious effort to stay in one place, or to return to Point A. Better tell a child to walk back every few minutes, explaining that the water will naturally push him astray. For yourself, pick a reference point: a pile of driftwood, a blowout in the dune, a beach towel, and keep in sight of it.

SUNBURN IS well named. The slower effects of ultraviolet light on human skin are akin to that of a flame. Exposed skin reddens as blood rushes to it, blisters develop to protect deeper tissues and under rare circumstances skin can actually burn. Destroyed cells release organic components that irritate sensory nerves, which carry a message - "Pain!" - to the brain. A suntan is the natural protective reaction to sunlight: Exposure to sun triggers the manufacture in skin cells of pigments that absorbs radiation and protect deeper tissues.

Blacks and other people with dark complexions have a protective head start and can sunbathe longer before burning, but everyone can suffer side effects of too much sun. Commercial lotions - the so-called sunscreens - effectively filter out ultraviolet rays. Another way to avoid burning is with progressive exposure. Start with short periods of sun and gradually lengthen them as tanning proceeds. Most people know their tolerances, but a couple of caveats bear mentioning: Chronic sun-worhippers - especially affluent Caucasians who coddle deep tans years after year - flirt with skin cancer from cumulative overdoes of solar radiation. In most forms this is the easiest kind of cancer to cure, but it can lead to serious disease.

A FAR MORE serious problem caused by exposure to the sun is called "heatstroke" by the American Red Cross and "hyperpyrexia" or "heat prostration" by medical texts.

By any name, it can kill. It involves a malfunction of temperature-control mechanisms that can't reinstate themselves spontaneously. Once excessive heat throws a victim's thermostat out of kilter, he's apt to die unless artificial means are used to reverse a runaway heating trend.

Normally the human thermostat is set at about 98.6 degrees F., but excess body heat affects the hypothalamus and interfers with its normal function. This is when the trouble starts - trouble that can compound itself into a fatal vicious circle. If the body gets too hot, the cooling mechanisms like surface blood-vessel dilation and sweating are delayed or weakened. As the body heats up, excess heat can inhibit the brain from turning on the cooling equipment full blast, which results in the brain getting hotter until the cooling systems shut down entirely. This can continue until higher body temperature kills brain cells and causes brain damage. An overdose of sun can start this runaway reaction.

Heatstroke symptoms may include any or all of the following: vertigo; unconsciousness; very flushed face; a strong, rapid pulse; elevated blood pressure, and dry skin since the sweating mechanism is blocked by the kaput body thermostat. These may lead to convulsions, coma and death. First aid - or, better yet, fast hospitalization - is needed to reduce body temperature so the hypothalamus can start working properly again. The experts recommend trying almost anything to reduce body temperature if it reaches 105 degrees.

Take the victim to the coolest available place where humidity is low. Strip him to increase cooling.

Aim fans at him to increase air circulation and evaporation.

Wipe him with cold, wet towels.

Sponge the body with rubbing alcohol, which evaporates (and cools) faster than water.

Apply ice packs.

Put him in a cold bath. One standard medical text prescribes ice-water baths; the Red Cross manual specifies cold water without ice. But then, the Red Cross also suggests that after undressing the victim the First Aider should use "a small bath towel to maintain modesty" - whether the victim's or the First Aider's remain unclear.

Gentle reader, dear friends, passing strangers: If anyone ever finds me felled by heatstroke and wastes any time on "modesty," I'll expire from apoplexy at such rank stupidity. Don't worry about fig leaves in potentially fatal situations. If a spare cloth is available, use it as a sponge. Delay meaningful treatment too long and the victim will have a sheet over his head soon enough.

Concentrate on lowering the body temperature and keeping it below 102 degrees, since it can quickly "rebound" to higher levels.

HEAT CRAMPS and heat exhaustion, though less serious than heatstroke, can lead to it if ignored. Both involve the sweating mechanism and the body's salt/water balance. The cramps come first, typically in the legs and stomach muscles. They result from too little salt in the body. Nerve control of muscles depends on electrical connections made by salt ions in the blood. When an unacclimated person sweats profusely, he expels salt in unusual amounts. This robs the body of sufficient salt to make neurological connections; brain messages don't get through, muscles go into spasm, and the person gets cramps.

Like the skin's ability to cope with heavy doses of sunshine, sweating improves with time. Once these glands get used to summertime work, their ducts reabsorb much of the salt constituents and recycle them, so someone getting used to hot weather may add extra salt to food for a few days and then gradually return to a normal salt intake.

When someone in a cool climate encounters the first heat wave of the summer he simply can't sweat as freely at first; each sweat gland is like a rusty pump and takes time to work up to maximum activity. An acclimated person can excrete nearly five quarts of sweat an hour; a newcomer to the heat does well to expel a quart and a half an hour. Obviously, the extent of perspiration depends on ample water in the body. Loss of that water through sweating means a lower supply until it is replaced by drinking. When cells in the brain's thirst center - again, another part of the hypothalamus - get dehydrated, the person gets the message to drink. But the message may be repeated after drinking since it takes time for the water to be absorbed. As a result you can drink too much and experience "water intoxication," when body fluids become too diluted and there aren't enough salt ions to perform the body's electrochemical work. Thus, muscle cramps can be a symptom of too much water or too little salt.

Heat exhaustion can occur after a few days in an unfamiliarly hot climate. First blood rushes to the capillaries to dispel excess body heat through radiation. This can rob vital organs of sufficient blood, so the capollaries then constrict leaving the skin pale and clammy (since sweating has been copious). The net result is a drop in blood pressure. Fainting occurs when not enough blood carries oxygen to the brain. The fainting spell itself can revive a victim, since after falling down the head is lower than before and lower blood pressure suffices to supply the brain. Here the body takes care of itself.

The lessons are simple enough: Overexertion and overexposure at the beach should be avoided until you are thoroughly acclimated. And unless you are absolutely fit, pamper yourself when planning to spend more than a few hours on a remote beach. If you intend to walk a few miles, pack along plenty of water or fruit juice and some salty snacks. (When sweating freely, a quart of fluid an hour is not an excessive amount to drink.) Remember that the last half of the distance may take a good deal longer than the first. For one thing, fatigue has set in. For another, if you set out with a falling tide, the walking will be easy along the wet sand; but return with a rising tide and footing is difficult in dry sand above the swash. If your tan isn't complete yet, carry some cover-up light clothes: a wide-brimmed hat, long-sleeved shirt, long pants, socks and sneakers. Loose, light-colored cotton fabrics are best because they reflect rather than absorb sun and let air circulate over the skin.

DON'T SNEEZE AT the idea of shoes on the seashore. For one thing, surface sand gets hot enough in the sun to blister bare feet. For another, rocks and broken shells found on some beaches can inflict nasty wounds. There's something in the combination of an irregular curved object and a sharp broken edge that makes a cruel cutter. Step on a sea clam shard and it penetrates; apply weight and it twists in deeper.

Elsewhere shoes are necessary so you can choose the surest footing. Exploring a Massachusetts breakwater barefoot. I couldn't step on the tide-bared barnacles and so instead stepped on green algae and slipped. Falling on a patch of the barnacles that looked no bigger around than matchheads, my arm was raked from elbow to wrist. The minute cuts, too shallow to hurt (at first), measured 15 to the inch and didn't heal for a month.

A SIDE FROM mollusks and stingrays, a variety of other animals can hurt - the cnidarians in particular. Call them jellyfish, but some apparent jellyfish - the comb jellies - are harmless to humans. Nearly transparent or luminous, they may have a single pair of long filaments with short branches to snare their prey. To avoid a tangle of zoological distinctions, let a simple rule suffice: Beware of jellyfish with many tentacles. They're the ones that sting.

These animals' notoriety depends on a tiny, fundamentally mechanical structure called the nematocyst - typically, a hollow cylinder containing a toxin and a long, coiled, microscopically barbed thread that springs out like a sharp, diabolical jack-in-box when anything touches its closed aperture.

Notably sluggish and delicate, the jellyfish cannot distinguish between likely food and anything else. Its nematocysts simply explode at the touch - even if a tentacle has broken off from the rest of the animal.

In the Portuguese man-of-war, each tentacle may have 750,000 nematocysis. The cumulative effect of several thousand minute poison-dipped weapons is extraordinarly painful and debilitating.

When one has bumped into a cnidarian, the next problem is to remove the tentacles as they continue to discharge venom. Wipe them off with a towel, sand or anything hand, one authority says, then apply alcohol, household ammonia, vinegar, lemon juice, boric acid, hand lotion, sodium-bicarb' paste; these are the standard salves. But Ray Manning, a Smithsonian crustacea man and veteran of beaches around the world, recommends Adolph's Meat Tenderizer. He regularly carries a shaker of it to sprinkle generously on jellyfish (or insect) stings. It acts on the foreign body the same way if softens chuck steak: by breaking down the proteins.

In East Coast waters, jellyfish are not often lethal; usually they just plain hurt. Because the larger varieties have geometrically larger numbers of nematocysts to hurt with, they can be very painful indeed. In addition, the toxin can be a real danger when delivered in large amounts.

The Portugese man-of-war, or bluebottle, is actually a colony of specialized, mutually dependent organisms, not a single individual. A warm-water oddity, it is most common along southern coasts but drifts from the Gulf Stream to the Outer Banks, Nantucket and the Vineyard. When they're seen near shore, word spreads fast. For one thing, its reputation for inflicting pain is deservedly widespread. For another, it is undeniably pretty. The long-tentacled animal stays afloat by means of a triangular balloon that rides the surface of the ocean. The gelatinous balloon or "sail" is an astonishing pale translucent electric blue, often with almost iridescent pink headlights. Surprisingly, the brainless animal can manipulate its sail to catch the wind and move in a chosen direction - like a skillful windsurfer. However nice they are to look, the man-of-war is a drifter to be avoided in the water. One swimmer stung by one off Florida died after the encounter - of heart failure, perhaps induced by the pain of several thousand nematocysts, which leave large welts. Many other people have been scarred and hospitalized by the mindless creatures. Nonetheless, they are not without merit. They shelter some fish; they are fodder for sea turtles and the giant sunfish. I've ever seen a calico crab make a meal of a little red jelly off Fire Island.

ONE FINAL HAZARD on the beach: the occasional threat of lightning. The dimensions of these electrical extravaganzas stagger comprehension: Sometimes five miles long but rarely than a pencil, a single bolt lasting less than one second can carry 100 million volts and reach a tempereature of 50,000 degree F., or five times as hot as the "surface" of the sun itself.

By all means get out of the water at the first hint of a thunderstorm. Probably the safest place to be on the beach is crouching down behind a dune - and keeping well below its crest. Since lightning often strikes the tallest local objects, don't hide under an isolated tree, bush or metal watchtower, which may just draw the next bolt like a magnet. (Seeking shelter in a forest is okay.) A source citing National Oceanic and Atmospheric Administration instructions says if you feel your hair stand on end - indicating that lightning is about to strike nearby - "drop on your knees and bend forward, putting your hands on your knees. Do not lie flat on the ground."

Remember that a little rain must fall everywhere - even at the beach. Resign yourself to a good rinsing and enjoy the spectacle. CAPTION: Illustrations 1 and 2, no caption, by Anne E. Lacy