Poas Volcano National Park

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Poas Volcano National Park

Poas Volcano National Park is located on the continental divide of the volcanic Central Mountain Range, and is about 40 miles north of the capital city San Jose. Poas is another of Costa Rica’s most active volcanoes, but its activity is quite different from that of Volcan Arenal. Poas is a compound basaltic volcano and has a slow, demonstrative activity of the lake kind.

Poas Volcano boasts the second largest crater in the world.
Poas Volcano boasts the second largest crater in the world.

At the rim of the volcano there are two craters. The primary crater is 1.5 kms in diameter (the second largest crater in the world) and has a round hot-water lake at the bottom which is very acidic and fumarolic. If it is clear enough to see to the bottom of the 300-meter deep crater, you will surely observe some type of activity ranging from fumaroles to bubbling emissions on the surface of the small rain-filled lake to actual geyser-type eruptions, but it is constantly changing. This crater has been the site of frequent eruptions since the first was reported in 1828 and has also greatly increased its emission of gases since 1989. Although it has regular small geyser and lava eruptions, the last major eruptions at the volcano were from 1952-54. Because of its geyser like eruptions, Poas is known as the largest geyser in the world.

A few meters back down the trail from the active crater overlook, a 1.5 km. trail leads off to Lake Botos, a densely forested dormant crater filled with rain water. A portion of this trail goes through an eerie-looking section of stunted forest. The trunks and branches of the small trees here are gnarled and twisted from the harsh climatic conditions in exposed areas at high elevations. At the Lake Botos overlook you'll be near the highest point in the park which is 2,704 meters.

Looking to the left of the crater you can see the deleterious effects of the volcanic gases that cause a localized form of acid rain. For several kilometers downwind from the crater the vegetation is brown and dying. On exceptionally clear days you can see the top of Arenal Volcano (60 km. distant) by looking in this direction. If you keep your eye on it long enough, you may be able to see the cloud of ash that accompanies an eruption.

At this elevation wildlife is not particularly abundant, but there is usually a fair amount of bird activity. Some of the more common species are the Fiery-throated Hummingbird, Sooty-capped Bush-Tanager, Slaty Flowerpiercer, Mountain Eleania, Black-billed Nightingale-Thrush, and Black-and-yellow Silky-Flycatcher.

As it only takes 90 minutes to drive the paved road to the volcano's summit, this national park receives more visitors than any other. On weekends and holidays it is very popular with local citizens as a picnic spot.


There is a visitors center in Poas Volcano National Park which is open from 8am to 4pm. One of the benefits of this is the Visitors' Center which presents a thorough explanation of volcanism and the natural history of Poás using a variety of entertaining and informative displays. It also has a cafeteria and a souvenir shop.

Getting to Poas Volcano National Park

• from San Jose take the highway to Alajuela

• from there, take the road to Itiquis and Fraijanes, following the signs to the volcano