Poas Volcano

Location: Poas Volcano National Park, Central Volcanic Mountain Range, 23 miiles north of Alajuela

Altitude: 8872 feet

This volcano has three craters, only one of them active. The live volcano is a crater 9/10 of a mile wide and 984 feet deep. It contains at its bottom the largest, active, boiling lagoon in the world, 1,148 feet wide and a cone, bubbling constantly with fumarole and geysers, 131 feet above the level of the boiling lagoon.

North of the active crater is the long-extinct Von Frantzius composite cone, the oldest crater in the central volcanic mountain range system. This dormant crater is located half a mile southwest of the active crater. This fellow gave up the fire and brimstone business some 7,500 years ago, and transformed itself into a cold water lake 1641 feet wide.  Water from the lake drifts down the mountainside becoming the Sarapiqui River that then flows eastward to the Caribbean coast.

Back in 1889, the volcano set off a powerful earthquake that knifed away a part of a hill, forming a forming a land pot that filled with water becoming Fraijanes Lagoon, a site that Costa Ricans have long treasured as a place to go for a Sunday outing.

There have been other eruptions. In 1910, a huge ash cloud was blown 26,248 feet into the air, with pluiform eruptions at the site creating the largest geyser the world has ever seen.

The 1952-1954 eruptions put up more ash clouds, thick with fire, rocks and underground noise. Since 1989, gas emissions have increased creating acid rain that damages strawberry and coffee crops west of the volcano.

The best time to visit the Volcano is May to November, the earlier in the day the better. Your walk will take you to the active crater for a look at the plumes of sulfuric smoke and water vapor and along natural trails leading to the Botos Lagoon.  It is one of the few accessible active volcanoes in the Americas. The Congo and the El Viejo Volcanoes are also in  Poas Volcano National Park.

For more information, read about our experiences exploring Poas Volcano on our travel blog.