Arenal Volcano

Location: Within Arenal Volcano National Park; 11 miles west of La Fortuna 


Altitude: 5,436 feet above sea level

Arenal Volcano is one of Costa Rica's most popular attractions, and for good reason. On clear nights lava flows can be spectacular, especially when viewed while soaking in a naturally-heated hot springs at one of the nearby thermal resorts.

Volcano aficionados have declared Arenal the third-most perfect volcanic cone in the world. It is also the youngest and most active volcano in Costa Rica, and one of the ten most active volcanoes in the world. Arenal is a stratovolcano, similar to Japan's Mt. Fuji.

Arenal has had several names throughout the years, including Arenal Peak, Rio Frio Volcano and Pan de Azucar (Sugar Loaf). In Spanish, “arenal” means “hill of sand,” and refers to the volcano’s ash, or sandy, slopes.

Just 3,000 years old, Arenal Volcano is considered a young volcano. Little is known about its early life, but it had been believed dormant from AD 1500 until 1968. Drawn by verdant slopes and incredible views, adventure lovers, hikers and naturalists regularly ascended to the volcano’s summit, often camping out in the cool crater.

On July 29, 1968, Arenal Volcano violently awoke. For the first time in over 400 years, the volcano began to spew red-hot lava rock. The eruption did not occur from its main crater, but instead from two new craters at the western side of the volcano. Eighty people and approximately 45,000 cattle, in addition to countless wildlife, were killed in the eruption.

The 1968 eruption wiped out area towns, including Tabacon and the original Arenal. Today, they lie flooded beneath Lake Arenal, which was created in 1979 for hydroelectric purposes. The largest lake in Costa Rica, the 21,128-acre reservoir provides almost 50% of Costa Rica’s total electricity, as well as water for farming and irrigation. Arenal Volcano National Park, adjacent to Arenal Lake, is an important watershed, providing over 70% of the lake’s water.

At just over 1,800º F, Arenal Volcano’s lava is considered to be quite cool, and this low temperature makes for thicker, more solid lava. Since the 1968 eruption, Arenal has continued to erupt on a daily basis – a phenomenon known as strombolian activity – and as the “cool” lava rock accumulates, the volcano grows almost 10 feet per year. Over the last 40+ years, a second cone has grown up next to the previous, and today, Arenal sports two twin volcanic cones. The volcano’s second cone is just a few feet taller than the first, and together, they form the world-renowned “perfect” volcanic cone.
 
Lava flows tend to change directions every six to eight months, and typically favor the southwest and/or northwest slopes of the volcano. Explosions shoot ash plumes more than half a mile above the volcano and send boulders the size of houses tumbling down the slopes. In addition to daily activity, there are infrequent major eruptions.

Volcanologists in Costa Rica constantly monitor Arenal's activity and warn that the volcano could have a major eruption in the future. The biggest threats are pyroclastic flows, a mixture of hot rocks and gases that can travel up to 50 mph, destroying everything in their path. Arenal Volcano National Park officials mandate that tourists stay on marked paths and keep a good distance from the crater.

Many hotels and ecolodges in the La Fortuna area cater to the awesome volcano view, which is best observed on a clear night.  Chato Volcano is Arenal's neighbor to the southeast, also located within Arenal National Park.