Sunrise at the summit of Cerro Chirripo: Even a meteorologistwould be hard-pressed to nameevery type of cloud that spreadsacross the landscape. (Kevin Charles Redmon/For The Washington Post)

To stand atop Cerro Chirripo, at 12,530 feet Costa Rica’s highest peak, and watch the sun rise over the Atlantic Ocean about 50 miles away, you must first excel at waking up in the dark. Four a.m. is okay; 3:30 is even better. At that hour, the stone floors of Base Crestones, an environmental research station that allows up to 60 backpackers to sleep in its spare dormitory beds each night, are cold enough to freeze your feet through two pairs of woolen socks. There’s a good reason for the unheated station’s nickname: the Refrigerator. Here, at 11,200 feet, mid-June might as well be mid-winter.

The first eastern glow of sunrise is still two hours away, but the summit of Chirripo lies two miles distant and more than 1,000 feet up. Now is a good time to find a head lamp and begin flexing the stiff leather of your hiking boots.

The mountains of the Talamanca Range run like so many vertebrae down the length of Costa Rica, northwest to southeast, and on a clear morning, their summits tear through the soft fabric of the low-lying clouds that form over the interior’s impenetrable forests. The view from here — to the east, the Atlantic; to the west, the Pacific — is awesome in its totality. Look south: That’s Panama.

There are plenty of thrills to be had in Costa Rica, a country that arguably invented eco-tourism as a form of sustainable economic development. But for all the jungle zip-lining, white-water paddling and quetzal-spotting that awaits the adventurous traveler, there are few moments as sublime as standing on the heights, wind-whipped and bleary-eyed, waiting for day to break. (Even Thoreau, deeply shaken by his 1846 ascent of Maine’s Mount Katahdin, understood this: “The tops of mountains are among the unfinished parts of the globe. . . . Only daring and insolent men, perchance, go there.”)

Yet Cerro Chirripo is hardly inaccessible. For even the scrappiest shoestringer, a modicum of planning and a warm sleeping bag are the only essentials. Oh, and a watch with three alarms — the more jarring, the better.

The bus from San Isidro del General, a regional seat on the Inter-American Highway, to San Gerardo de Rivas, at the base of Chirripo National Park, leaves daily at 6:30 a.m. from the central market. The 13-mile road to San Gerardo quickly becomes a series of deep ruts and potholes stitched together by the occasional patch of ungraded gravel. Paralleling the Rio Chirripo Pacifico through swaths of untouched jungle, the ride, if you can stay awake, is spectacular.

My partner, Caitlyn Olson, and I both fall asleep. The bus driver idles outside the park’s ranger station a mile south of town, and barks mildly at us in the rearview mirror until we scramble out the back door, trailing our backpacks.

The Ministry of Environment and Energy oversees all of Costa Rica’s parks and preserves — more than 25 percent of the country is protected — and applies its own peculiar bureaucracy to permits within Chirripo National Park. In the dry season, December to May, it’s recommended that you have reservations up to 12 weeks in advance. This involves wiring money to a Costa Rican bank account. It’s easier to simply show up outside the agency’s San Gerardo office early in the morning and claim one of the first-come, first-served permits. (There is no rainy season in Costa Rica, according to tourism boosters, only a “green season,” but even then a permit is easy to come by.)

A lone park official greets us at the gate, looking as if he dressed in a hurry. He rubs the sleep from his eyes as he fills out our paperwork. For a $10 daily fee, plus $15 a night for lodging at the station, as cheap as any hostel, the park is our playground.

San Gerardo itself is an outpost of just 305 ticos, as Costa Ricans call themselves. At its center are the four landmarks familiar to any Costa Rican town — a church, a school, a bar, a soccer pitch. The church is ochre- and copper-colored, the two-room school purple. The Roca Dura, serving canned beer, stays open as long as anyone is paying. The pulperia, or general store, has a long bench under its awning, where you can sit and watch schoolchildren in untucked uniforms play futbol.

The fields that unfold over the low shoulders of the Talamanca are devoted to coffee, dairy cows and subsistence farming. On the road to the park, you’re far more likely to encounter a pack horse laden with milk cans than anything motorized. A doctor visits twice a month.

Past a handful of family-owned hostels, orchid gardens and hot-springs baths, the washed-out road winds up into the foothills, splits a few times and peters out. From here, it’s nine miles to the Crestones research station. Nine miles is not a lot — but the accompanying 6,700 feet of elevation gain is. The truly well-caffeinated hiker will make the climb the same day she arrives in San Gerardo; for everyone else, there’s a bed waiting in town.

Casa Mariposa, run by the ineffably low-key Jill and John Titan, is painted the whimsical pastels of a butterfly’s wings and built into a rock outcrop. The low-slung A-frame feels like the type of home Peter Pan’s Lost Boys might retreat to: bamboo ceilings, windows cut anywhere they’ll fit, hammocks strung up out back.

The 40-something American transplants bought the guesthouse three years ago, after ending up in San Gerardo by accident. “The area reminded us a lot of the Pacific Northwest, where we’re from,” says John. Living at the gate of a national park isn’t so rough, either. “The landscape up there looks like a mix of Arizona and the Arctic. It’s very much not like the rest of Costa Rica.”

At least half their guests come to climb Chirripo, so the Titans play outfitters, too, storing excess gear for those in the park, lending out warm layers and drawing maps of day hikes in the nearby Cloudbridge Reserve.

And for the muddy and the weary, on their way down and out of the park, Casa Mariposa’s memory foam mattresses, stone bathtub and refrigerator stocked with Imperials are welcome touches.

The route up Chirripo begins just outside Casa Mariposa’s door, and in the pre-dawn cool, Caitlyn and I shoulder our backpacks — sleeping bags, butane stove, three days’ worth of food — and begin climbing. Each kilometer is signed and named, and early on they pass quickly — “The Monkeys,” “The Oaks,” “The Beautiful Plain.” Through the cloud forest, the path traces a high ridge, with views falling away on both sides. In the thick shade of the canopy, the forest floor smells of ferns and wet earth. Halfway up, we rest on the porch of an abandoned ranger outpost and drink from a spring-fed tap.

For several miles, we play leapfrog with a boisterous group of Brits, a Royal Air Force helicopter squad on leave from Afghanistan’s Helmand province. Soaked in sweat, the Chinook pilots sit on their packs and smoke cigarettes as we pass.

Soon, the epiphytes and moss give way to dry scrub and open savanna. Above 11,000 feet lies the paramo, the northernmost extension of the Andean tundra. An impenetrable cloud bank rolls up the valley. The kilometer markers begin to feel a bit like stations of the cross — “The Burns,” “The Repentants,” “The Last Step” — and when the rain arrives, just past the turnoff to Monte Sin Fe, the mountain without faith, its chill is welcome.

Around a final corner, the green roof of the sprawling research station comes into view. The topography here is post-glacial, scoured and pocked by tongues of ice as they retreated 25,000 years ago. Kettle lakes and moraines dot the sweeping, U-shaped valley; along the far wall tower los crestones, smooth pillars of rock that jut skyward like thumbs. Far to the south spreads the Savanna of Lions, home to pumas and jaguars. And standing like sentinels above the research station, ensconced in the clouds, are twin 12,500-foot peaks: Cerro Ventisqueros and Cerro Chirripo.

The station, Base Crestones, has computers with wireless Internet (thanks to solar panels on the roof), cold-water showers and an echoey mess hall. At each long wooden table, a different language is being spoken. It’s early afternoon, but eight hours of hiking have left me feverish. As the freezing drizzle tapers off outside, Caitlyn boils water for powdered broccoli soup and we spoon Nutella from the jar. Hours before it grows dark, I’m zipped into my sleeping bag. I fall asleep to the din of the helicopter crew down the hall, who packed plenty of libations to keep warm.

Getting an “alpine start” at 3:30 a.m. is less painful than expected. Because we slept in every layer we own, we’re hiking within 15 minutes. Ahead of us, a thin line of head lamps bob in the darkness, making their way up the valley. (Hangovers notwithstanding, the RAF guys know a thing or two about getting up at awful hours.)

We pick our way through the scrub, and in the pale light of the setting moon, large boulders cast otherworldly shadows. The sky begins to creep toward colorlessness, then takes on a pink tinge. We shed our lamps and long sleeves, thinking that each false summit will be the last. The final approach is the most dramatic, dropping down into a narrow saddle and then climbing straight up a rock scramble — the kind of hiking that requires all four limbs.

The peak is crowded, as several dozen of us, all in garishly colored parkas, huddle for protection from the elements. Using all our loose gear, I construct a windscreen for the stove and make coffee. From here, most of what you see is sky. Even a meteorologist would be hard-pressed to name every type of cloud that spreads across the landscape.

The sun’s first light explodes through the thin atmosphere, setting the peaks and outcrops below us aflame in every shade of orange. Color begins to return to the depths of the valleys, and the troubled waters of the lakes tucked inside them shimmer like fool’s gold. The morning is excellent and fair.

With the postage-stamp fields of San Gerardo scattered far below, it’s hard not to think about what awaits our homecoming: the thermal baths and Casa Mariposa’s warm kitchen.

But Cerro Ventisqueros spires just over Caitlyn’s shoulder, and our permit’s good for two more days. Tomorrow, after another restless night in the Refrigerator, we’ll lace up our boots in the dark and, through the sleet and through the fog, scramble to its summit for one more chance at sunrise and the sublime.

Redmon is an itinerant journalist and a Middlebury Fellow in Environmental Journalism.