Arenal Volcano
l Tortuguero lArenal Volcano l Monteverde Cloud Forest l Guanacaste l Puerto Viejo de Limon l Carara National Park l Tiskita Jungle Lodge l Corcovado National Park l Manuel Antonio NP l
 Arenal Volcano of Costa Rica is located just west of the small town of La Fortuna. This smoldering mountain and its rumblings dominate the local landscape.
The chances of a big eruption anytime soon are remote (see below), but lucky visitors on a clear night can still see the glow of the furnace that fuels the mountain. Arenal has also created unique hikes and adventures on the mountains and rivers of the area, easily accessible to visitors based in or near La Fortuna. Read on for the fascinating history of the volcano and the things you can do in its vicinity.
The Explosion In 1968, Arenal was a quiet tree-covered mountain with only a small amount of steam venting in the crater at the peak. On July 29, at about 7:30 in the morning, it erupted with such force that shock waves were registered as far away as Colorado in the USA. Three craters opened simultaneously on the west side of the volcano during a devastating eruption. As a black cloud of dark volcanic sand and hot gases rose rapidly above, a glowing orange hot mass of rock, smaller stones, sand and hot gases were blasted out at velocities of almost 2000 feet per second and roared down as a hot avalanche over the landscape. The effects of this and subsequent blasts were devastating. The heat of the avalanche roasted everything in its path and trees and other vegetation were instantly dehydrated and some carbonized. The rocks smashed into objects like bombs. Impact craters up to 3 miles distant pockmarked the landscape with holes that were up to 80 feet wide and 13 feet deep. Some areas in the direct path of the explosion were 100% cratered. Houses were torn apart, thousands of cattle died, two small villages were destroyed and some 87 people were killed. In total, an area of nearly 5 square miles was devastated by the eruption. Effects of the 1968 explosions can still be seen today. Lying at the base of the volcano on the west side are large boulders which were once sections of the volcano's wall, hundreds of smaller shattered gray rocks blasted out during the eruptions, and a few huge tree trunks still standing in a mute testimony to the devastation. After its 1968 eruption, Arenal gained fame as one of the world's most active volcanoes and became the subject of many studies by international teams of scientists. From investigations of the region's soils (which record the effects of past activity), they determined that Arenal was about 7000 years old, and had major eruptions every 800 years or so followed by periods of declining activity before quieting down again. The Volcano Today Today Arenal is in a period of gradual declining activity that has been ongoing for nearly 40 years, and may continue for decades. It has two peaks. One is an old peak which still emits small amounts of steam. The other is a new peak formed during the 1968 eruption and has grown about 700 feet in height since then and continues to grow. The new peak is where the major activity takes place.
 Arenal has small rumbling eruptions, releases of steam and other hot gases, and continuous flows of lava that can be seen glowing orange on clear nights. Thick, pasty flows of lava move slowly out of this peak, and large pieces break off as rocks and tumble rapidly down the volcano's steep slopes. Starting out of the crater at 1800°F, this pasty lava is thicker than liquid lavas and forms jumbled piles of rocks known as blocky lava flows. From a safe distance within the National Park or at lookouts such as El Silencio or Arenal Observatory Lodge, one can observe the impressive spectacle of "live" lava breaking off the sides and front of an advancing lava flow. These hot lava rocks gain momentum as they move down the steep slopes and may attain speeds of 60 miles an hour or more. They crash against other rocks on the uneven rocky volcanic surface and are hurtled into the air from the violent impacts causing many to smash and shatter into smaller pieces. At night, these orange lava rocks seem to be exploding. From October 1991 to September 1992 one lava flow traveled beyond the base of the volcano at a rate of about 2 feet per hour and crushed its way through the forest in the level plains in front. This flow is about 60 feet high and hundreds of feet across and stretches over a mile. One could still feel heat emanating from vents on it three years after it stopped moving. Today, plants are colonizing this flow and will eventually cover it completely. An excellent pair of trails called Las Coladas and Los Tucanes in the national park wind through rainforest and go over the flow giving spectacular views of the mountains, lake, forests, Arenal volcano and the huge mass of rocks that make up the flow.
On rare occasions, Arenal produces rapid flowing avalanches called pyroclastic flows. These are surges of hot lava rocks, small rock fragments and gases that race down at speeds up to 75 miles an hour. Pyroclastic flows can be caused by an eruption, collapse in an advancing lava front on a steep slope, or a break at the peak of the volcano. These are unpredictable and occur sporadically. Years may pass without any major flows, or suddenly in one day many can occur, such as on May 5th 1998, when 23 flows occurred in a period of 6 hours. Taking maybe less than four minutes to descend, these generally stop on the slopes, near the base of the volcano or a little beyond. Pyroclastic flows are the most dangerous element at the volcano, and for the remote possibility of their reoccurrence, visitors must not pass beyond the designated safety limits in the national park or elsewhere. Other Activities in the Area
 When visiting Arenal Volcano, you might want to give yourself at least two full days in the area due to a great variety of attractions to be found nearby. Arenal Lake just in front of the volcano to its west, offers fishing opportunities, boat tours, and windsurfing on its northwest end. If you like hiking, the nearly 30,000 acres of Arenal Volcano National Park offer several forested trails, and in addition there are other trails outside the park worth visiting. Arenal Hanging Bridges, a private reserve has rain forest of outstanding beauty and a trail system that travels on the ground and over bridges with great views of the forest canopy. For the physically fit a steep trail leads up to the mysterious crater lake at the nearby (inactive!) volcano Chato. Another steep, yet much shorter trail leads to the gorgeous 125 foot tall waterfall of the La Fortuna River.  If you are a birdwatcher, the area offers great birding in habitat of premontane rainforest of the Caribbean slope. There is a ski-lift type Gondola ride and several cable canopy tours. Plenty of lodges offer horseback riding on rural roads, and one can go rafting on nearby rivers. If you like to see a variety of wildlife while riding in a canopied boat, the Rio Frio/Caño Negro boat trip is excellent. These are just a few of the many options available.
There is a lot to see and do in this area, and by following a few sensible safety precautions when visiting the region near the volcano, you can enjoy the spectacle of seeing one of the world's most active volcanoes in an area of incomparable beauty.
l Tortuguero lArenal Volcano l Monteverde Cloud Forest l Guanacaste l Puerto Viejo de Limon l Carara National Park l Tiskita Jungle Lodge l Corcovado National Park l Manuel Antonio NP l
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