By the time we arrived at Termas Los Pozon, the moon shone overhead. But the gatekeeper, sitting in a ramshackle hut, simply accepted our $10 entry fee and waved our car down into the darkness with a nod.
"Park at the bottom of the hill and follow the 100 steps down to the ravine bottom," he said. "You'll see the pools there. We close at 6 a.m."
We had come to Patagonia's lake district -- a vast wilderness punctuated by volcanoes, glacial lakes and waterfalls that divides Chile and Argentina -- to explore the healing power of hot springs, part of indigenous folklore for generations. What we found were a series of spa lodges focused on wellness and pampering, as well as a medicinal centre full of travellers seeking what many consider a hidden "fountain of youth."
Termas Los Pozon, a lakeside ski centre on the outskirts of Pucon, roughly 800 kilometres south of Santiago, Chile's capital, is home to natural hot springs where visitors can bathe in six rock pools under the stars as the icy Liucura river flows by.
To enter the pools, which run along the river's edge, we walked along a dimly lit pathway. Steam rose off the surface of the water, and as we passed ghostly bathers I thought of woodland fairies relishing a primordial celebration of nature. Slipping out of the chilly night air into the 38-degree waters, it was easy to fall under the spell of the hushed surroundings.
Days earlier, we had set off from San Carlos de Bariloche, Argentina's northern Patagonia outpost, for our first stop: the 138-room Termas Puyehue hotel and spa in Chile. Located near a volcano, its open-air aguas calientes have drawn the local Mapuche people for generations -- often with their horses and cattle.
Our guide, Maria Jose Machuca, showed us how locals dig their own thermal pools in the soft banks, scraping away layers of pebbles and mineral clay to expose waters rich in sodium, potassium, calcium and magnesium. "People come to bathe and connect with Puyemama," she said. "That's what they call the spirit of Mother Nature."
There is also a more formal spa in the area. Its thermal pools -- two housed in a solarium lodge and another al fresco -- attract visitors with chronic illnesses or undergoing physiotherapy. As manager Consuela Santana explained, the waters' magnesium is a laxative, sodium lowers blood pressure and lithium acts as an antidepressant. But "the most important quality is the pH balance," she added, "which is very alkaline. When you have a lot of stress, your body gives off acid and the water neutralizes it."
We heeded Santana's warning to soak for only 15 minutes in the piping-hot 40-degree pool before braving the frigid plunge pool. This was a wise move, since the experience left me tingling with a curious awareness of the warm blood coursing through my veins. We then tried the fango spa treatment, which left our skin silky smooth after being exfoliated with mud from the river.
Who knows if it was the heat of the water or its lithium content, but that night I slept like a baby, enveloped in a cocoon of contentedness.
The following morning, we took a lingering drive north to the Termas Huife, set in the Andean forests near the border of Argentina. Here, a handful of lodges with wood-burning stoves, bathtubs that fill with the area's waters and private decks, are a stone's throw from a spa and outdoor pebble-bottom thermal pools.
I tried the suggested therapy for improved circulation -- soaking in the thermals and plunging into the icy river -- but could only take so much of the drastic temperature change. Then I found the outdoor hydrotherapy pool overlooking the river, where spouting cascades of thermal water banished the knots in my shoulders.
The final leg of our trip saw us return to Argentina's Andes. We arrived at night in the tiny mountaintop settlement of Copahue, a village that shuts for half the year, owing to the four metres of snow it receives.
Even though there isn't much charm to the weather-worn town, some 15,000 visitors from Buenos Aires and Neuquen (the nearest city, four hours to the east) flock here during the summer. They seek the curative effects of the sulphuric mud, algae-rich waters and vapour baths that have been recognized by the World Health Organization as among the most varied in the world. After days in the tranquil wilderness of the lake district, Copahue's hospital-style setting -- which included mandatory medical exams and the overpowering stench of the bubbling, puce-green waters -- left no mystery: There was some serious healing going on here.
On our first day in the sulfur baths, aptly named chancho (or "pig bath"), my husband was practically attacked by two older gentlemen who insisted on helping him slather mud on his back, telling him how Copahue had cured their arthritis.
"I arrived yesterday and could barely bend my knee, but look at me now after a few treatments," one man said, swinging his leg around. "It's great for the bones."
There is even an official medical director of thermal waters posted at Copahue, one Ana Maria Monasteria. The waters' recuperative impact "isn't magic," she told me. "The effects of soaking in the hot springs, the relaxing powers of fango, and being in the fresh mountain air has a great influence on a person's psyche."
A little moonlight and stardust doesn't hurt, either.
Pack your towels
LAN Chile ( http://www.lanchile.com) offers flights from major Canadian cities through Santiago to San Carlos de Bariloche. From there, you can rent a car from Bayo Turismo & Aventura ( http://www.bayoturismo.com) and drop it off in the town of Neuquen.
WHERE TO GO
Hotel & Termas Huife: Camino Pucon-Huife Km. 33, Pucon, Chile; 56 (45) 197 5666; http://www.termashuife.cl. Rates from $187 a night, including breakfast and access to hot springs.
Termas Los Pozones: Road to Huife, 34 km from Pucon. Day passes at Termas de Huife are $8.
Termas Puyehue Hotel & Spa: Termal Ruta Internacional 215, Km. 76, Osorno, Argentina; 56 (2) 293-6000; http://www.puyehue.cl. Rates start at $140 a night, including breakfast and access to hot springs.
Christina Gonzalez: 54 (11) 4326 4777; firstname.lastname@example.org. This Buenos Aires-based travel agent helps foreigners navigate reservations for hotels and plane tickets and beyond.