Poás volcano is a powerful symbol of the geothermal forces that formed Costa Rica. When the mist and clouds part you’ll see the sulfuric, bubbling, green rain fed lake at the bottom, surrounded by smoke and steam rising from fumaroles. Water from the lake is constantly seeping through cracks in the hot rock, evaporating and building pockets of steam. When the pressure in these pockets exceeds the weight of the water above, the steam breaks through in geysers that rocket up to 820 feet (250 meters) high. Don’t worry about getting a shower though, the crater is 1,050 feet (320 meters) deep. At almost a mile (1.6 km) across it’s also the largest active crater in the world.
A modern visitors center (wheelchair accessible) and small museum explains and interprets the geothermal and ecological attractions in the park. A cafe serves coffee and hot drinks—as much to wrap your hands around to warm them as anything else—sandwiches, and snacks.
Poás is active, but don’t expect to see a full fledged eruption or even any lava flow here, the most recent period of eruptive activity ended in 1954. The last major activity was in 1910 when nearly a million tons of ash was ejected along with an immense column of smoke and steam.The volcano provides an excellent if extreme example of the effects of acid rain. Around the caldera, and for several miles downwind, the vegetation is stunted brown and black by the tainted moisture that precipitates from the omnipresent clouds near the peak.
Hiking and Walking Trails
Trails that lead through cloud forest stunted and twisted, not only by volcanic emissions but the rigors of the cold windy high altitude habitat. Lake Botos fills an extinct crater at the end of one trail, and is home to many cloud forest birds including hummingbirds, tanagers, flycatchers, toucanets, Costa Rica’s national bird the clay-colored robin, and the area’s most famous avian resident, the resplendent quetzal.
The paved, level, 0.3 mile (0.5 km) crater overlook trail starts at the visitors center and takes about 15 minutes each way. There is a viewing platform surrounded by a short wall. The Botos trail, 0.9 miles (1.4 km) branches off the overlook trail just before the viewing platform and climbs gently to the lake. The 0.6 miles (1km) Escalonia cloud forest trail is an excellent route to see all of the birds that live in the park, and two of the endemic species—Poás squirrels, and escalonia trees easily identified by their unique pagoda shape.
Poás is above the frost line, and temperatures below freezing are possible. Nearly constant winds and saturating humidity contribute to biting cold at the rim.
When to Visit
Poás clouds over well before noon year round and in the rainy season it may not clear off at all.
The best time to visit is always early in the morning but you can use the drop down menu to see what the weather is likely to be like in the month you’re planning to travel.
Quick Facts Poás Volcano National Park
Protecting 5,600 hectares with elevations range from 2400 to 2708 meters (7874 to 8885 feet) Poás is a small but important park. You can find cloud forest and tropical rainforest-upland habitats within the boundaries.
The story of conservation at Poás began in Tennessee’s Great Smoky Mountains National Park in the 1960’s. Mario Boza was a student when he visited the park in the United States and was so impressed that he developed a plan to manage the area around Poás Volcano in a similar way, presented it as his masters thesis, and pursued its implementation. How the plan was adopted as an integral part of the birth and development of the National Park system in Costa Rica is described in David Rains Wallace’s book, The Quetzal and the Macaw.
Most tour operators in San José offer day trips to Poás for $US 60-120 depending on what other attractions are included. There are no accommodations in the Park.
From San José take the Pan American Highway west to Alajuela, across the highway from the airport. You will come into town on Calle 2. Follow this all the way through town and it becomes route 130 to Itiquis and Fraijanes and is signed for the National Park. If you are uncertain, ask before you leave Alajuela, once you are on the right road out of town it takes you directly to the park.
Alternatively, from San José take highway 3 or 5 to Heredia, then 126 north through Barva, and Roble to Varablanca where you turn left towards Poasito and follow the signs 10 km to the park.
Daily departures from Avenida2, Calles 12/14 in San José at 8:30 a.m. make one stop in Alajuela’s central plaza at 9:00 a.m. on the two hour journey to the park. There is only one return bus, don’t miss it at 2:30 p.m. (Tuasa company, $US 3, bus 1241, phone 2233-7477).