Poás Volcano: Looking Into a Giant Crater

Poás Volcano, in Alajuela, lets you do something unusual: get almost all the way to the edge of an active crater and look inside. What you see is a huge hollow about 1.5 km wide, with rock walls and, when conditions allow, a lake of hot, turquoise water.

The Hot Lagoon

The lake inside the main crater, known as Laguna Caliente, is one of the most acidic lakes on Earth. Its color, its fumaroles and the smell of sulfur change with the volcano’s activity. At some stages the lake even disappears completely and forms again years later.

Much more than a crater

The park also protects Botos Lagoon, an old, inactive crater filled with cold water and surrounded by cloud forest. At this altitude grow plants such as the “poor man’s umbrella” (sombrilla de pobre), with giant leaves, and birds such as hummingbirds and the clay-colored thrush, Costa Rica’s national bird.

Tips for your visit

• Tickets are bought online, and time at the viewpoint is limited for safety.
• The park may close without notice when volcanic activity increases: check its status before you leave.
• Bring a jacket; it is cold at the top and the weather changes fast.
• If clouds cover the crater, wait a few minutes: sometimes it clears.