The Poás Volcano is an active stratovolcano in north-central Costa Rica with the world's second-largest volcanic crater. The volcano is located in Poás Volcano National Park, part of the Cordillera Volcánica Central Biosphere Reserve.
The Poás Volcano is an active stratovolcano in north-central Costa Rica, within Alajuela Province. Its summit reaches 2,697 m (8,848 ft). It has erupted 40 times since 1828. The most recent significant eruption was in April 2017. It was its largest explosive eruption in years.
The 2017 eruption was mainly driven by water heated at the summit crater lake/vent area, generating a "phreatic" eruption. Visitors and residents were evacuated. The volcano and surrounding park were closed for nearly 17 months, with a 2.5 km (1.5 mi) safety perimeter established around the erupting crater. The volcano briefly erupted twice in September 2019.
The Poás Volcano is the second-largest volcanic crater in the world. It measures 1.5 km (0.9 mi) in diameter. This crater is quite active, with frequent small geyser and lava eruptions.
Rainwater has formed a lake at the bottom of the crater. The lake is known as the Laguna Caliente ("hot lagoon") and is located at a height of 2,300 m (7,500 ft) above sea level. It is approximately 300 m (985 ft) wide and 30 m (98 ft) deep and is one of the world's most acidic lakes.
The southern lake, Laguna Botos, fills the second (inactive) crater that last erupted in 7500 BC. It is cold and clear and surrounded by a cloud forest.
The volcano is located in Poás Volcano National Park, which is one of the major attractions in the Central Valley region and one of Costa Rica's most visited National Parks.
Poás Volcano National Park
Poás Volcano National Park covers an area of approximately 65,000 ha (16,000 acres) and was established in 1971. It is part of the Central Conservation Area, an administrative area that SINAC manages for conservation purposes in the central part of Costa Rica, notably the volcanic regions of the Cordillera Central.
Poás Volcano National Park is one of the four national parks within the Cordillera Volcánica Central Biosphere Reserve.
Depending on the conditions, visitors can walk to the edge of the main crater. However, on April 13, 2017, the park was closed to visitors due to an explosive eruption on the evening of April 12. Further explosions caused the park to be closed until August 2018. Over the years, the park has been frequently closed to visitors due to precautions regarding water vapor and sulphuric gas emissions.
Two more craters comprise parts of the park: the extinct Von Frantzuis crater and the Botos crater. Lake Botos is a beautiful cold green-water crater lake with a diameter of 370 m (1,200 ft). The Botos crater has not erupted for about 7,500 years. Well-marked trails lead to the two inactive craters, conditions permitting.
Flora and Fauna
Poás Volcano Park is part of the Talamancan montane forests ecoregion.
A variety of wild plant and animal species are found here. These include the Poás magnolia bird species, the clay-colored robin, the black guan, the resplendent quetzal and varieties of hummingbirds, tanagers, flycatchers and toucans. Mammals within the park include coyotes, rabbits and marmots.