Jungle vacation in Costa Rica. There's no TV, radio, newspapers, or telephone. But here's an exciting chance to live the vicarious life of a Roger Tory Peterson, or Tarzan.

THIS is Costa Rica, and it's a jungle out there. Not as much as it used to be, unfortunately. Deforestation has chomped through this small Central American country like Godzilla at a salad bar.

Outcries from environmentalists worldwide, plus government intervention, have protected some of the virgin forest here from total devastation. In the past decade, about 10 percent of Costa Rica has been set aside as national parks.

As a result, there are a few large patches being protected, treasured, and explored. Naturalists, scientists, ornithologists, biologists, and what are referred to here as ``specialized tourists'' are now able to share the jungle experience.

If you haven't outgrown your childlike curiosity about all those creepy-crawlies that make many grown-ups squirm, and don't mind following the tracks of an unknown beast over mountain and swamp - only to have the pawprints suddenly disappear into a stream, read on.

One of the most interesting albeit remote areas to explore is here at the Marenco Biological Station.

A flight from Miami to San Jos'e, Costa Rica; a taxi to the bus station; a six-hour bus trip to a one-dog town; an overnight on a hard cot in a stifling motel; a morning ride in the back of an open truck to a pier; a three-hour boat ride on river and ocean and - voil`a! - you're here.

No sooner had our Zodiac maneuvered between the jagged outcrop of lava rocks to hit the beach when David, one of our group, dropped to his knees. Not so much from exhaustion or gratitude as from his obsession - the tough and tiny Theromato mymrex.

``It's a little ant with giant mandibles. Very rare. We can't figure out how this ant carries its delicate eggs without damaging them,'' he said, peering under a mango leaf. He was collecting a few of the ants to send to a friend at Harvard University for further study.

Stepping over David, we trotted behind Gordo (Fatso) and Flaci (Skinny), an oxcart team that lugged our luggage up a steep, stony path leading to our cabins. These were simple, rustic, and comfortable - set on an open clearing between jungle and sea.

Wide decks opened toward the Pacific to scoop the prevailing west winds and offer spectacular sunset views.

With dorm-style cabins and bunk beds, a combination lodge and dining hall, and separate toilet facilities, Marenco is not plush but certainly comfortable by jungle standards.

There is no TV, of course; no radio, newspapers, or telephones. And not enough ice! Fortunately there is electricity - between 5:30 p.m. and about 9:30 p.m., or whenever the the generator quits. Whichever comes first.

Amenities for guests are simple. What you do get, along with three square meals a day, two sheets, a towel, a bar of soap, and a six-inch foam rubber mattress, is the exciting chance to live the vicarious life of a Roger Tory Peterson, Jacques Cousteau, or Tarzan. And the distinct possibility of sharing your shower with a toad.

The two dozen or so folks in my group were a mixed bag. There were a few slightly eccentric entomologists; rather serious botanists from California, collecting palms; some birders of all persuasions; a photographer; and a few assorted children.

The station is available for the serious researcher, or for more casual exploration by interested tourists, amateur naturalists and photography buffs.

Tourism is in fact, encouraged. As resident naturalist Woody Moise said, ``The tourists are our bread and butter. It's they who literally support the station here.'' And in part, tourism is doing the same for the many parks throughout Costa Rica.

Woody answered our questions - from scientific to silly - with wit, knowledge, and patience. His interest and concern for this unique area were quickly absorbed to a degree by everyone through slide presentations, lectures, and after-dinner chit-chats.

Woody was also our guide as we hacked our way through remote forests, explored local islands, went on skin diving expeditions, and field trips.

The optional jungle excursions into adjoining Corcovado National Park are heavy-duty - not for the weary or squeamish.

Activities at the station can be at your own pace. Less active folks can spend a quiet and rewarding day on the balcony of their cabin with a pair of binoculars. The skies come to life with scarlet macaws, black and vermilion tanagers, flocks of emerald-green parrots, and toucans, as they fly from forest to field.

The surrounding rain forest is carefully etched with miles of marked trails, ending at freshwater, stream-fed pools or remote salt water beaches. These, too, may be explored at one's leisure.

``Just don't go alone, and watch where you step,'' Woody wisely advised. A recent photo of a python with the girth of a mortadella salami caught just outside the lodge make the point. It's still out there, we were told - with a lot of its friends.

For all the insect life in the forest, Marenco is surprisingly free of biting bugs. I have been pestered by more mosquitoes on a warm August night in New England than here. With one exception. Dave, our intrepid ant collector, did identify one intruder.

``Crenatogaster,'' he announced with some pride, as we picked the ubiquitous little black ants from our bunks and dropped them off the balcony.

After long, busy days exploring, evenings were spent in the lodge comparing notes. Tales of birds and monkeys spotted, plants gathered and, yes, even ants identified were shared with enthusiasm.

Before the generator quit and the lights went out for the night, we'd drag our mattresses onto the balconies to catch the shifting breezes and be lulled to sleep by exotic jungle serenades under the full moon.

No need to set an alarm clock. Territorial howler monkeys, who have the dubious distinction of being the world's loudest mammals, wake up before dawn. And when a howler gets up, so do you.

If you go

Lodging at Marenco runs about $65 a day, including meals. Rates for those doing educational research are less. Field trips are additional, according to availability and space. If, for instance, a group of researchers charters a trip, there is room for a few hitchhikers at no additional charge.

There is an endless amount to see and explore right within the 1,250-acre Marenco Biological Reserve. Be sure to bring binoculars, sturdy hiking shoes, a canteen, camera, and sunscreen. Clothes should be lightweight and dark in color.

For complete information, contact Marenco Biological Station, PO Box 4025, San Jos'e 1000, Costa Rica, Central America.