WE cast off into the dark night and head out onto Limoncocha Lake -- a body of water that is filled with 500 hungry caymen (South America's alligator) and an abundance of piranha, and is surrounded by jungle. Our guide, Maurizcio, shines a powerful spotlight around the perimeter of tall grass. Suddenly, two eyes glow red about 100 feet ahead. Our first cayman has given himself away. We edge over to within 15 feet of him. The spotlight now reveals seven feet of prehistoric reptile arched into attack position with a foot-and-a-half of wide-open jaw showing rows of sharp, jagged teeth.
Disdainful of this invasion of privacy, the cayman gives a tail thrash to the water and instantly vanishes into the depths of the lake, where he can remain for as long as three hours.
The guide turns off the boat engine, and under a star-filled sky we sit quietly and listen to the jungle work its magic. Parrots, thrushes, herons, flycatchers, and kingfishers -- just a few of the area's 464 species of birds -- join monkeys, crickets, and cicadas in a primeval improvisa-tion of caw-caws, cries, clicks, hoots, and hollers.
Earth has few frontiers left in 1985, but the Amazon jungle remains one of them. This giant salad of vegetation spreads across nine South American countries in a land mass 10 times the size of Texas. From it comes one-third of the earth's oxygen, and -- I was amazed to learn -- half the world's bird species, 18,000 plant species, 3,000 kinds of fish, and one-fifth of the earth's fresh river water.
It was in Ecuador's portion of the Amazon, called Oriente, that I spent four days exploring. Aboard the Flotel Orellana, a comfortable triple-deck floating hotel, our tour cruised down the Napo River, the headwaters of the Amazon. The four-day, three-night program (another runs five days and four nights) is put together by Metropolitan Touring of Quito, Ecuador.
From its home port of Francisco de Orellana, the Flotel travels about 12 miles up the Napo River to the edge of the rain forest. Here groups leave the ``mother ship'' via two motorized dugout canoes for an overnight excursion to Limoncocha Lodge, where we encountered the caymens.
Our dugout canoes glided down the Napo River, threading their way into the opening of the tiny Jivino River and passing deeper and deeper into Amazonia's interior. Thick exotic vegetation, banana trees, and palms flanked the river, as we passed an occasional Indian hut with a dugout canoe parked ouside the front door.
We stopped to visit Isla Pompeya, an Indian village with a Roman Catholic mission. This isolated island houses a small church with walls of bamboo and a roof of thick thatch. Seating is on backless benches. The church is an interesting mix of orthodoxy and village make-do: The colorful dugout canoe is used for an altar, and the church bell -- outside the front door -- is an old oxygen tank that is banged with a rock to make it sound.
The island also houses a small anthropological museum of Napo era (1188-1480) artifacts, including Indian pottery, bows, arrows, spears, and knives. Three 7-foot long blowguns are displayed with their deadly darts dipped in curare, a poison made from 16 plants. Indian tribes living in the Oriente still use these today for hunting game.
About an hour later we arrived at Limoncocha Lodge, our home for the next two days. Situated in a tiny Indian village of a few native huts, the two dormitory-style thatched roof lodges stand a few hundred feet from caymen-filled Limoncocha Lake. In view out the front door is a dramatic hanging bridge that spans a 100-foot ravine.
Our first jungle adventure begins as a passenger steps out of the boat and onto a semi-submerged tree, kicking up a cloud of mosquitos. Since most of us are wearing a heavy dose of insect repellent, we walk through them un-scathed.
A thermometer would tell you it's 85 or 90 degrees F., but this is deceiving. In a tropical rain forest, the temperature is only a tiny part of the story. The other is humidity, which feels like 200 percent here. It makes the jungle seem to sweat. Our group moves under the tall green canopy of forest through a maze of vines and leaves on a trail cleared by Indians, but still requiring an occasional hack of a machete from our guide (especially, I noticed, when the cameras are clicking).
Most of the action takes place right on the rain forest floor. Butterflies, birds, stink bugs, beetles, and ants are the ``regulars.'' Our guide points out a poisonous black Conga ant the size of a wasp crossing the top of a large palm leaf. A few hundred feet farther along the trail an army of ``leaf cutter'' ants marches across a log, each carrying a small half-inch section of leaf. Maurizcio uncovers a four-inch nonlethal centipede, and we each endure 10 seconds of a hundred tickles as it crawl s up our bare arms.
The giant of the rain forest is the kapok tree. Soaring 150 feet into the sky, it bursts out like a firework into branches at the very top. At 500 years old, it joins the fig tree (from whose huge trunk one could carve out a small home) to form the tallest tops of the Amazon rain forest. The kapok tree is draped in hanging vines that make terrific swings. Few in the group can resist the urge to grab one for a flying whirl.
It is said that the jungle has more eyes than leaves, and if you include insects, I guess it's true. But I have to say that my image of jungle, admittedly formed as a kid watching ``Tarzan'' on Saturday-morning TV, was of tree limbs lined with squawking parrots and macaws, anaconda snakes slithering across the forest floor, monkey antics overhead, and ocelots on the hunt.
Our guide reassures us that these creatures are here all right, but just not at the same time we are. During the day they retreat deep into the rain forest. This was a disappointment, but only a mild one. Most jungle ``action,'' as well as much of its beauty, is provided by the birds. In a few hours we spot over 60. The exquisite sangrid sits atop a branch near the lake as does the anhinga, an aquatic acrobat who dives into the water, spears a fish with his sharp bill, then flies home with dinner.
The greater ani is an exotic bird with shiny blue-black feathers. Not usually one for bird-watching, I found myself riveted to this extraordinary display of beauty and color.
After two days at Limoncocha Lodge, I'd had a good dose of South American jungle and was looking forward to a hot shower and clean clothes, as well as to three days of civilization in Quito, with side trips to markets in the Andes Mountains.
We returned to the Flotel, showered, and then ate lunch at a nearby hacienda, a working estate farm which houses a few caged ocelots, anaconda, and parrots. The delicious native lunch included fresh catfish from the Napo, beef, heart of palm, yucca chips (like potato chips made from yucca), all washed down with lemon grass tea (a real hit with our group).
The Flotel Orellana, with its 20 double cabins, 2 four-berth cabins, and 1 six-berth, made a comfortable base of operations from which to explore the jungle area. The fan-cooled double cabins are small (7 by 10 feet), but adequate for two nights aboard. Each cabin has hot water and a shower. The flotel also has a dining room, sun deck, and a lounge. In the evenings after dinner, lectures were delivered in Spanish, English, and German.
The cruise price is $375 per person double occupancy for four days, $465 for five. Included is the cost of flights to and from Quito, transportation from the airport (in our case a 2 1/2-hour bus ride), accommodations, meals, and the services of guides.
While this trip is a genuine jungle experience and was spent in relative comfort, there were moments that could be considered ``semi-roughing it,'' which might not appeal to everyone. We had an unplanned walk of a few miles in tropical heat and humidity when our jungle tractor broke down. And there were also a few climbs up steep, slippery riverbanks and some jumping in and out of boats. No innoculations are required, though some guidebooks suggest them. Practical information: How to book: Reservations can be made in the United States through Adventure Associates, 5925 Maple Avenue, Suite 116, Dallas, Texas 75235; telephone 1-800-527-2500. Or you can book directly through Metropolitan Touring, PO Box 2542, Quito, Ecuador. How to get there: There is excellent air service to Ecuador. Eastern Airlines has daily flights leaving from New York and Miami as well as Los Angeles and San Francisco.
Christopher L. Tyner's trip was partly sponsored by Eastern Airlines and Metropolitan Touring.