Plastic hospital-type bracelets are strapped on our wrists as my husband, Thom, and I check into the Tabacón Grand Spa & Thermal Resort. “Makes it easier to identify the bodies,” the front-desk clerk says with a wink. “Be sure to notice the signs showing the evacuation route, and if you’re driving, back your car into the parking space so that you can get out quickly. Answer your phone immediately,” he tells us, “even in the middle of the night, because we will call you in the event of an eruption.”

Although the bracelets are really to allow hotel guests free access to the hot springs, the warnings are part of the procedure for checking into a hotel located at the foot of one of the world’s most active volcanoes, Arenal, of Costa Rica.

After being dormant for 400 years, Arenal erupted with fury in 1968, burying 5.8 square miles (15 km²) in hot lava, rock and ash. Three small towns were destroyed. The roads in the area are still pocked with Volkswagen-size craters and huge, black boulders dot the green pastures where cows now graze peacefully.

Pools are paved with hardened black lava.

The volcano has been active every day since 1968, with two or more eruptions nearly every hour. Hot rocks and lava tumble down the southwest face during eruptions.

A potentially deadly avalanche occurs without warning every two to three years. The guest rooms at Tabacón are located on a small rise, but the Tabacón hot springs lie downhill, directly in the volcano’s path.

Dangerous? Yes, but what an unbelievably beautiful setting for a rain-forest resort and spa with lush tropical gardens, cascades and waterfalls, and steamy hot pools of geothermal mineral water bubbling up directly from the heart of the volcano. There is no place like it on earth.

The Tabacón resort is located between the town of La Fortuna and Lake Arenal, halfway between Costa Rica’s two international airports, San José’s Juan Santamaría and Daniel Oduber Quirós. From San José it takes about three hours to get to the resort on a very crooked, but newly paved, road.

Although closer to Liberia, it takes about the same time, on an equally crooked road that is so full of pot holes it required our driver to spend as much time on the left side as the right. This was nerve wracking on the many blind, hairpin curves with sheer drop-offs and no guard rails.

From either direction, the drive is picturesque. Imagine a tropical Bavaria, complete with chalet-like houses and cows grazing on steep green mountainsides. A stop for a coatimundi to cross the road, and another stop to see a troop of sleeping howler monkeys draped over the branches of a huge tree reminds us of where we are.

Even when shrouded in clouds, the volcano makes its presence known with deep, thunder-like rumbling as we grab our umbrellas, provided by the hotel, and walk to dinner at the restaurant by the hot springs. An open-air, multi-terraced dining area overlooks a big, steamy pool fed by the Tabacón River flowing down the slope.

The nights are cool because of the altitude, which makes the hot springs a favorite evening place. After dinner, we change into bathing suits and test the waters of the various pools and waterfalls, which get progressively hotter as we climb the hillside. We find a quiet and secluded little pool that is just right, and luxuriate under the starry sky. This experience alone is worth our trip to Costa Rica.