Costa Rica is home to five – yes FIVE – active volcanoes, and they are all popular destinations for adventurous explorers and thrill seekers alike. Although many of them have direct, easy-to-navigate paths, some of them are a bit more challenging (or off-limits) – even for avid hikers and fitness buffs. Are you ready to explore Costa Rica’s active volcanoes? Don’t forget to grab your hiking boots – it’s a long way up.
Rincón de la Vieja Volcano
Often referred to as the “Colossus of Guanacaste,” the Rincón de la Vieja Volcano contains at least 9 major eruptive centers. Measuring 1916 meters high, the majority of recent eruptions have come from a prominent crater containing a 500-meter-wide acid lake (that’s right – an acid lake!), also known as the Active Crater. It is not recommended that you swim, explore, or even go anywhere near the Active Crater, as it is a large, boiling pot of acid that can range in color (from blue to green to grey) with a temperature of anywhere between 20 degrees Celsius (68.0 °F) to 58 degrees Celsius (136.4 °F). Activity is currently in the southeast portion of the volcano.
The Poás Volcano is a whopping 2708 meters high and has two summit crater lakes. The Southernmost lake, named “Botos” is a cold, green-water lake, and it has not erupted for at least 7500 years. The other lake is located in the main crater. It is 290 meters deep with frequent small geyser and lava eruptions. Geothermally heated, the main crater is likely the second most acidic natural lake, with a pH of around zero. The Poás Volcano National Park is often closed due to volcanic activity, so make sure to do your research before making the trip.
Arenal is perhaps one of the most popular and widely explored of the active volcanoes. At 1657 meters high, Arenal is incredibly active and has a bad reputation – with good reason. In 1968, Arenal volcano exploded and killed several people, primarily by throwing incandescent bombs as far as 5 kilometers away from the vent. Although the volcano hasn’t exploded recently, it consistently emits pyroclastic flows from the vents at the summit and on the upper western flank. Don’t let that deter you, though. Arenal volcano is a beautiful hike and a great place to mountain bike.
Double the size of Arenal, the Irazú Volcano is massive – it covers more than 500 square kilometers, is 3432 meters high, and has at least 10 flank cones on the southern flank. All of Irazú’s eruptions in the last 10,000 years have been remarkably explosive, and the active crater contains a small acid lake. The last major eruption of Irazú was from 1963-1965. It caused heavy damage to infrastructure in San José and the neighboring communities. The last reported activity was a magnitude 7.6 earthquake on September 5th. It’s a must-see stop if you’re visiting Costa Rica!
Turrialba is an active volcano that has been incredibly explosive in recent years – including January, March and April of 2017. Visitors were once able to hike down into the main crater, but the increased volcanic activity – including ash and rock slides – has forced the surrounding Turrialba Volcano National Park to close. The summit has three craters, and the largest has a diameter of over 50 meters. On a clear day, both the Pacific ocean and the Caribbean Sea are visible from the summit.
Note: It us unclear as to whether there are actually 5 or 6 active volcanoes. Some sources also state that Tenorio Volcano is active.