THE EVERGLADES is a low place in a low land. Entering the park from the eastern gate near Florida City, the land looks like nothing so much as African veldt. One expects to see giraffe, elephant herds, perhaps a lion or two. The two-land black-top road seems to lead 40 miles into what looks like nowhere and nothing at all like Pogo's swamp. What you see when you motor toward Flamingo is a sudden surcrease from gas stations, neon, supermarkets and fast-food joints, and miles of flat grassy land.

The tourists are often disappointed. The rangers and naturalists at Flamingo have heard it all before, have listened to thousands of plaintive questions. Where are the alligators? The impenetrable swamps? The vine-choked jungles?

Alligators do not line the road, cheek-to-jowl, with otter and Florida panther for the benefit of the tourists. The Everglades is 1.4 million acres of primal land snatched from the developers of southern Florida to remind us of how Florida once looked, and it shows itself only to those who take the time to explore it patiently. It is a fragile ecology hanging by a thread of fresh water dammed up in Lake Okeechobee, and because winter is the dry season when wildlife seeks the dwindling water supply and the all-important fish are concentrated, that's the best time to go.

The Everglades is a world where many endangered species are making their last stand. Extinct elsewhere, they flourish here under the protection of the Park Service, and if you're lucky and can stand up to the mosquitoes, you will see creatures you will never see anywhere else, birds and animals you never thought you would set eyes on . . . the southern bald eagle, the Everglades kite and the American crocodile, for example.

Pull back the curtains in your motel room in the Flamingo Inn, and look out onto Florida Bay. They say the water averages only four feet deep and if you had to, you could walk to Key West. Just beyond the palm could be an American egret. The plume trade at the turn of the centuury once nearly wiped out the egret. Guy Bradley, a ranger at the time, was shot defending birds like this from poachers after a law was passed to protect them. dYou can see a marker to Bradley on your way to breakfast near the steps going up to the restaurant.

You'll find no riot of colorful tropical blossoms in the Everglades and not a single flamingo, except possibly an escapee from the racetrack at Hialeah Park. The flamingo learned to avoid Flamingo during the height of the feather trade. But before breakfast you can look through the telescope mounted on the breezeway by the restaurant and spy on a nesting pair of bald eagles living on a key in the bay. Over your orange juice and eggs, you might see the porpoises come into the water below.

But the brown pelican, that huge joke of a bird, red-eyed, ungainly, standing knee high to a man, is the treat. Once he nested everywhere on the Carolina and Louisiana shores, ut his habit of dining on fish we carelessly poisoned with chemicals nearly made him extinct. Now he is largely confined to the Everglades, but how he does own the place! Every post in the marina at Flamingo has its solemn sentinel so motionless that visitors sometimes mistake them for decoy. But watch out when fishing boats come in later in the day. He'll almost literally knock you down in his haste to get some of the leavings from the catch. His 6 1/2-foot wingspread brushes against the shin of many a bystander in his single-minded attempts to get a free dinner.

As he gulps down high billfuls of heads and tails, the fishermen from time to time shoo him away as a farmer would chase away an impertinent chicken. But he only retreats from the cutting table to a safe distance and watches his chance to close in again. Above his head a sign asks fishermen not to feed him, for he gets flled up with bones and heads of fish which do not contain the protein that whole fish supply. And he is so accomplished a thief, this huge bird who cannot survive very far from the glades, that his appetite must certainly be spoiled.

Birds are all very well, but perhaps you came to see an alligator. Take the tram into the bush, and you'll get plenty of glimpses of these descendants of the dinosaur lying immobile among the mangrove, close by the casnal that Henry Flagler built on the 27 miles of Everglades that the state of Florida gave him for his coastal railroad. Flagler's dream was to drain and develop the everglades, but the brackish tides came in instead, and the Everglades were left to the original occupants. And to the mosquitoes. The coconut palms have developed the "withering yellows" and will all be gone, by next year they say, but the mosquitoes have never been so virulent. Insecticide spray is passed among the tram passengers before each ride, yet nothing really helps. They go right through your clothes.

You'll see no alligators on the Whitewater Bay cruise, but plenty of herons and vultures watch the boat slide by on the canal approach. The herons stand solitary, contemplating life, but the vultures seem to like the company of their kind as they group themselves on the bank like a convention of undertakers, which they actually are, dining on the corpses of small animals.

The naturalists point out the sights like bus conductors. It is easy to see that they love the whole world of the Everglades, the twisted roots of the mangrove, the thin marl that serves for ground cover, the strange assaulting strangler figs, the little green tree frogs and the fluttering zebra butterflies. "Tell them in Washington how we need water," they beg their passengers. "They move so slowly, and we need it so badly."

Water is vital. A vast complex web of canals dug in the 1880s by the U.S. Corps of Engineers controls the flow of water for the eastern portion of the Everglades. Water divered for agriculture north of the park left the Everglades so parched during two particularly dry years that the survival of many of America's endangered and rare species was treatened. In 1970, Congress at last passed a law guaranteeing a minimum water supply for the east park, but the law has no teeth without a required pumping station which, 10 years later, has not been built. The threat of a jet airport close by the boundaries has been averted.

The naturalists' evengelism for this park is contagious. They know their guests are secrety trying to make every floating log into an alligator, but they want them to see more, taste the salty pickleweed, sigh with them over the damage Hurricane Donna did with her 180-mile-per-hour winds, take joy in the laughing gulls overhead, whose black feet are tucked neatly up against the wind.

It is impossible to see it all in a short visit, but Anhinga Trail on the way back to Florida City is a wonderful change from Flamingo. It offers perhaps the best alligator viewing in the park, and you can lean over from the guided walkway and stare into their half-shut eyes or study the configuration of their scaly backs. The walkway leads through the famous river of grass annd through glades inhabited by egrets and water buzzards where garfish in the alligator holes are stacked up in winter like cordwood. And until you see the water buzzards swimming completely submerged except for their snake-like neck and bill, you will never quite understand how birds can be descended from reptiles.

A night, two nights, a week perhaps, and it would still be impossible to know this primitive land which is larger that the state of Delaware. As in the fable of the blind men and the elephant, each visitor will see a different park. One will call it coastal prairie, another a piney woods, and still another a world of narrow waterways where gentle sea cows graze shyly and sea turtle still come ashore to lay their eggs on shelly beaches. Only one road crosses the Everglades; much will always be hidden.

The existence is precarious, threatened by run off from residual pesticides and chemical fertilizers, and canals and irrigation which deplete its water supply. A whole chain of animal and plant life hangs in the balance, dependent on man for the water that is so necessary for survival.

It may make you feel better about the mosquitoes to know that you also are part of this chain. The blood the mosquitoes take from you is simply the beginning of the food chain from insect to fish to bird to mammal and round again.