WHEN I FIRST HEARD ABOUT EL CIELO, the forest in the mists, I thought it must be a mythical place. I could hardly imagine a cool, verdant cloud forest, with ferns, orchids, macaws, and lofty alpine meadows, all within a day’s drive of the Texas border in the dusty state of Tamaulipas. Although it was named a biosphere reserve by the United Nations back in 1985, El Cielo (which means “the sky” or “heaven”) has remained something of a secret, hidden high within the eastern folds of the Sierra Madres. Clouds drifting inland from the Gulf of Mexico, trapped by the mountains, linger and drop more than 120 inches of rain a year on the forest, creating a treasure trove of biodiversity—a rare crossroads where a jumble of flora and fauna from north and south come together in startling proximity.

El Cielo has been protected, in part, by its remoteness. It lies less than three hundred miles south of the border, but it feels as mysterious and otherworldly as any place I’ve been in Mexico. And it’s not an easy place to visit. Getting there is difficult, and there are no travelers’ amenities within the cloud forest other than a couple of research stations and, on the far edge of the forest, a primitive lodge in a tiny village named Alta Cima. The entire reserve is officially off-limits to the general public—the government is still working out a policy to protect the place while balancing the interests of tourism and the local economy—but the reserve’s administrative office, located in Ciudad Victoria, about fifty miles north of El Cielo, will usually grant permission to visitors who express an interest in learning about the cloud forest’s unique ecology. (We faxed our request to the office and received a prompt reply by phone.) With no fences or entry gates to mark its boundaries, El Cielo currently operates on the honor system.

The State of Tamaulipas maintains a research station called El Canindo in the upper reaches of the cloud forest with dormitory-style bunkhouses that must be reserved in advance. They were booked on the only nights in March when my husband and I could get away, but we were able to reserve a room with bunk beds at El Pino, the tiny lodge in Alta Cima, which, a friend who had stayed there told me, is a step or two above camping in a tent. (The hot water at both places can be intermittent at best.) The villagers who run El Pino keep an office in Ciudad Victoria through a nonprofit group called Terra Nostra (when you call for reservations, you should be aware that no one there speaks English).

For our first night in El Cielo, we arranged to stay at the other research station, Rancho del Cielo. It has been administered since the sixties by Texas Southmost College, part of the University of Texas at Brownsville, more recently in conjunction with the Gorgas Science Foundation, a Brownsville-based nonprofit organization dedicated to conservation and teaching. (Because Rancho del Cielo was known to so many scientists and researchers, it lent its name to the whole biosphere.) Ordinarily, Rancho del Cielo is open only to students, researchers, and twice a year, small groups of birders. But we happened to be arriving between scheduled student groups, and Larry Lof, the station’s director, agreed to help us discover what makes El Cielo such an ecological treasure.

The only way to get to El Cielo is by car, and the closest border towns are Brownsville and McAllen, where you can buy food and water and exchange your dollars for pesos. Before crossing, it is necessary to buy Mexico car insurance (Sanborn’s, a reputable company, has offices in San Antonio and most border towns). In Reynosa, just across the border from McAllen, we made the required stops at the immigration and nearby Banjercito (state bank) offices, completing the paperwork for taking our pickup into Mexico and paying $10 for a car permit, and emerged with a silver car-shaped permit to stick on our windshield.

Right away we realized that reaching El Cielo would be something of a test—an ascent to heaven through various trials of fortitude. We had already violated the first rule of road travel in Mexico by scheduling an appointment at our destination, the timing of which left little leeway for the vicissitudes of traffic, weather, road hazards, and law enforcement. In fact, the drive from the border to El Cielo, which usually takes about six hours, would take us seven with no stops.

The first test was an unexpected trial by water—the first thirty or so miles of Mexico Highway 97 south of the border were flooded from a downpour the day before, and we had to drive on faith, following the wake of other cars and trucks through the deep slosh. We were heartened by the sight of the “Green Angels,” the bright green tow trucks operated by the government for the benefit of tourists, waiting at the other end of the flood.

After about a hundred more miles, we merged with Mexico 101, heading toward Ciudad Victoria. The next hurdle was the trial by construction—miles and miles of single-lane traffic along sheer drop-offs and detours onto dirt roads. Once the ambitious improvements to the highway are completed, the driving will be considerably easier. (On our return home, we took a different route, through Monterrey and Laredo, and found the driving less stressful.) It was the trial by truck, though, that was the most harrowing. Once we took the clearly marked bypass around Ciudad Victoria to head south on Mexico 85 toward El Cielo, the surface of the road became washboard bumpy and the truck traffic had us pinned in, with truckers in both directions often trying to pass on blind curves. We began gauging the relative peril of various stretches of road by counting the roadside shrines, little more than crevices carved into rock ledges.

Things got much better when we passed the turnoff to Tampico, which siphoned off most of the traffic shortly after we crossed the Tropic of Cancer, announced by a simple road sign and an almost immediate, dramatic change in scenery. Every little mud-and-wattle house was decorated with bright splashes of tropical color from the bougainvillea vines that had spread across roofs and facades. The mango trees in huge groves along the road were in bloom, and the scent was so heady we rolled down our windows, regretting that we didn’t have time to stop at La Morita, a famous mango emporium offering mango juice, pies, and jellies.

As we neared the turnoff to the town of Gómez Farías, which lies at the edge of El Cielo, we began climbing gradually; in the distance, surreal rock outcroppings punctuated vast stretches of patchwork-quilt fields. Gómez Farías, which must be one of the longest and narrowest villages in Mexico, is probably as far as you should go by car unless you have a pickup or sport-utility vehicle. The town consists of a tiny, picturesque plaza and a long string of houses, small shops, and cantinas lining the road, with a dramatic drop-off on both sides. By the time we reached the small house where we were to meet Larry Lof for our journey up to Rancho del Cielo, I was almost dizzy from the dramatic views, the scent of mangoes, and the gorgeous profusion of tropical flowers. Looking up into the mountains toward El Cielo, we could see brilliant patches of lavender, which I realized were huge redbud trees in bloom.

Rancho del Cielo is a two- to three-hour hike from Gómez Farías, but we packed our gear into one of the two trucks that Lof uses to shuttle students up there and headed east at a sign indicating the boundary of El Cielo. While the entire reserve covers 355,000 acres and four major ecological zones, the cloud forest itself is confined to a much smaller area: 7,680 acres, or 12 square miles. We soon began to traverse different ecological zones; there are so many subzones, or microclimates, Lof told us, that if we were going faster, we would pass a different one every minute. When we left Gómez Farías, we were still in the tropical lowlands, with plants growing wild that I recognized from my own garden and local nurseries in Austin—shrimp plants, begonias, crotons, and avocados, all much larger than I had ever seen them. Lof pointed out the chaca tree, with its burnt orange bark that was peeling back like a bad sunburn.

As we reached the ridge at the beginning of the cloud forest, the temperature dropped quickly. Even when the lowlands reach temperatures higher than 100 degrees, Lof said, the cloud forest remains comfortable, seldom getting out of the 70’s. Lof had told us that the best time to visit is the rainy season, from May to September, when everything is in bloom (although roads may wash out and even hiking can get messy), but it was hard to envision a more profuse display of foliage. A good rain over the past week had coaxed the ferns into unfurling, and every available surface was covered with epiphytes—the clinging plants, like bromeliads and orchids, that are not parasites of their host tree but live on air and water. My reverie was broken only by the need to winch the truck up a couple of slippery spots.

Miraculously, the logging companies that worked in the area until the sixties left most of the old-growth forest undisturbed; they were much more interested in the conifers found in the drier range above the cloud forest. As we continued upward, the trees got taller and the floor of the forest got darker. Our trip was beginning to feel like a journey back through time to the forest primeval. In fact, said Lof, some scientists believe that El Cielo is a relic forest, the kind of forest that existed across the continent 50 million years ago. “There are very few places like this on earth,” he said. “This little pocket of forest is where North America meets South America. You have jaguars together with mountain lions; you have northern trees like sugar maples and oaks and sweet gums covered with southern epiphytes.”

It took us two hours to make the six steep, rocky miles from Gómez Farías to Rancho del Cielo, which lies at the heart of the cloud forest. I was surprised to learn how small the station is—only 57 acres. Most of its rustic cabins were built by students. When we reached ours, I was startled to find a gravestone nearby, covered with freshly cut flowers. We learned that the former owner of Rancho del Cielo, Frank Harrison, a Canadian who had first come here in the thirties and had offered his hospitality to visiting scientists over the years, had been murdered in 1966 by transients left behind by the retreating logging companies. It was a reminder that we weren’t in paradise after all and that everything in the forest is vulnerable. And of course, Lof reminded us, there are the inevitable serpents here—including several species of rattlers and the fearsome fer-de-lance, one of the most poisonous snakes in the world.

The next morning before dawn, a student researcher came by to wake us up and lead us to a special outlook on the edge of the mountain where we could watch the sunrise through the mists. As the morning symphony of birds began, I could identify the plaintive whistle of the thicket tinamou, the downward-scaling trill of the singing quail, and the familiar carping of the green jay. There was even the distinctive squawk of a military macaw, so called for its camouflage-green color. More than 250 species of birds have been observed in El Cielo, according to Fred Webster, a former regional editor for the Audubon Society who lives in Austin and leads birding expeditions to Rancho del Cielo every June.

Later, we walked farther into the forest with a student named Juan Arias who had promised to find one of the mountain trogons that were announcing their presence in the treetops with piercing trills. The treetop canopy of oaks, maples, and sweet gums was so high and dense it was difficult to spot birds perching among the bromeliads. Although I’m only the most casual of birders, I felt a thrill at finally glimpsing the scarlet breast and long black-and-white barred tail of this northern cousin of the legendary quetzal.

When it was time to leave, we had to backtrack all the way down to Gómez Farías before driving on our own up to Alta Cima (if you prefer to hike, it takes about two hours). We tried not to look down from the narrow, rock-strewn road at the sheer drop-off, although the view of the lush valley below was spectacular. Fortunately, our pickup, which is not a four-wheel-drive, was up to the task, spinning its wheels in vain only once.

Our first stop in Alta Cima was at a small cafe named La Fé, which was built, along with the lodge, El Pino, to help the local people earn a living by catering to occasional travelers (they are no longer allowed to engage in logging or farming outside the limits of their village). After our rather harrowing ascent, we felt somewhat chastened when a Volkswagen bug came bouncing up the road to park beside the cafe, where we made arrangements for dinner that night and for a trip by horseback up the mountain the next morning (hiring a guide and two horses for the day came to about 80 pesos, or $10).

The lodge, with its basic concrete floor and separate bathhouse and outhouse, is about half a mile from the cafe. We sat on the swings of a child’s swing set outside, drinking the beer we had brought with us and unwinding to the soothing sounds of sunset: the faint strains of mariachi music from a radio, the clink of a cowbell on a heifer ambling home to dinner, the braying of hungry burros, the laughter of children playing in a nearby field. We walked down to the little cafe, where the women who work there had already prepared our nopales (strips of peeled prickly pear cactus) in mole sauce—delicious, like a spicy gumbo—beans, and fresh, hot tortillas.

We slept well that night—until we heard the deep-throated growling of some unknown creature prowling around the lodge. I switched on a flashlight and was about to investigate until my husband, a former Green Beret who served in Vietnam and taught jungle survival school in Central America, persuaded me that it was better to bar the door and wait until morning. After all, there are bears, jaguars, and mountain lions in the mountains. The next morning, I tried to imitate the sound we had heard for Eduardo, our guide, but I must not have sounded very fierce because he said it must have been a tecolote—an owl. I’m convinced we heard something scarier—maybe the tayra, a giant weasel known as “the old man of the mountain,” that Larry Lof had told me about.

It was only a two-hour ride by horseback (a hike would take a little longer) up an old logging road to El Canindo, the other research station, and to the tiny village of San José, which is decorated with fences made from the rusting doors of old logging trucks. There we were able to buy soft drinks and sit under the trees to rest and listen to the silence. Along the way, we had passed through a broad zone of tall pine trees, all laden with bromeliads and Spanish moss, and a lovely meadow that could have been in the Smokies or the Ozarks.

On our way back down to Alta Cima, we passed several groups of students on their way up to El Canindo, some walking and some riding. One jeep was so packed that young men were hanging on to either side and one was clinging to the roof. We exchanged greetings and quick observations as they passed. They seemed as thrilled about going to El Cielo as they would be about a concert or a soccer match—a good omen for the future of the cloud forest. I was reminded that when I had exclaimed over the beauty of the place to one of the students at Rancho del Cielo, he had replied, “That’s why they call it heaven.”

for permission to visit el cielo and to make reservations at El Canindo: Call or fax Salvador Vallejo, who speaks English, at El Cielo headquarters (011-52-13-12-32-42). A room with three beds  costs 78 pesos (about $10) a night per person. Cash only. Visitors usually take their own food.

For reservations at El Pino Lodge in Alta Cima: Call Terra Nostra (011-52-13-12-33-53) and ask to speak to Sergio Medellín, who does not speak English. A room with bunk beds costs 25 pesos (about $3) a night per person. Cash only.

For information on birding at Rancho del Cielo: Call Fred Webster (512-451-1669).

Carol Flake is a writer who lives in Austin.