Poás Volcano National Park
Barely an hour from the capital, the Poas volcano rises to an altitude of 2,700m. It has three main craters. The largest crater, with a diameter of 1.5 km, is one of the largest in the world, and is 300 m deep. The crater is filled with an acid lake with a PH of less than 1, making it one of the most acidic lakes in the world.
A volcano and a national park: the Poas volcano
Sulphurous fumaroles are the volcano’s main emissions, some reaching hundreds of metres in altitude. Two other craters are part of the national park. The laguna del Boto is filled with clear water and was last erupted 7500 years ago. It is easily accessible and observable. The third, Von Frantzius (the German scientist who first observed it in 1861), is difficult to access.
This stratovolcano has been active for 11 million years, but it was only in January 1910 that a huge explosion followed by a column of smoke over 8,000 m high rose above the cone, spewing ash and rocks for miles around. Since then, the volcano has experienced frequent phreatic eruptions.
Poas Volcano National Park
Access to the Poas volcano is very easy, and the road from Alajuela is absolutely magnificent. You’ll pass through the rich cultivation specific to volcanic regions, where strawberries, cabbage, coffee and flowers are grown all year round.
A wide path leads to the main crater. Another path leads to the second crater, El Boto. Afterwards, a short, easy stroll takes you through the high-altitude tropical forest that makes up the bulk of the national park’s vegetation. You can also admire magnificent specimens of tree ferns and the poor man’s umbrella (Gunnera Manicata).
The main inhabitants are hummingbirds, trogons including a few quetzals, toucans, and a few mammals such as bats, weasels and marmots. However, it’s not the wildlife that makes the trip worthwhile, but the volcano.
The whole park is well laid out, and at the entrance a small museum on vulcanology and a few stores welcome visitors.
It is advisable to visit in the morning (the park opens at 8:00 a.m.), as the summit is usually covered in clouds by mid-day.