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The summit area of Poás Volcano is only about an hours drive from the capital city of San Jose through Heredia. Driving from Atenas through Alajuela, takes about one half hours. The roads pass through some of the most important and spectacular coffee growing areas of Costa Rica, and display magnificent views of the Central Valley.
Poás has an altitude of 2,708 meters (8,884 feet) above sea level. It is one of the most spectacular volcanoes in Costa Rica, with a breathtaking scenery. It has produced excellent soil for cultivation and has considerable potential for producing energy from hydrological and geothermal resources.
 Besides the main crater, Botos Lake and the von Frantzius cone, there are at least half a dozen piroclastic cones in the surrounding savannah woodland of Redonda and Bajos del Tigre. These cones are made of ash, lapilli, fusiform bombs and small lava flows.
There are four main habitats in the park, areas with little or no vegetation, an area of arrayans, a stunted forest, and a cloud forest. Examples of the flora include small cypress, tucuico, small cedar and small cypres. The dwarf forest predominates in this area.
Some of the mammals that live in the park include Marmots (which are marsupials), Shrews that are amongst the smallest mammals in the world, Bats and over 79 bird species like Sooty Robins, Black Guan, Quetzal and the Emerald Toucanet.
The summit contains a number of explosion craters, and one of them contains a lake. Poás is one of the main tourist attractions for Costa Rica, but violent explosions occasionally occur here. You can see that there is almost no vegetation and the whole area is covered by ash.
Poás is a stratovolcano with several eroded calderas, cones, and two crater lakes near its summit. Poás has erupted at least 39 times since 1828 and is in state of nearly continuous mild activity. Most of the eruptions are phreatic, caused by the interaction of lava and the water in the crater lake. Explosions vary in strength. Some explosions eject material about 1,500 feet (500 m) above the lake. There is steam rising from the active crater lake. The lake (and steam) is very acidic, with a pH less than one. Temperatures as high as 185 F (85 C) have been measured at the crater lake.
 In 1989, the crater lake at Poás gradually drained away. Later, researchers found a pool of liquid sulphur about 6 feet (2 m) in diameter. This was the first observation of a liquid sulphur lake on the surface of the Earth. The sulphur is probably remobilized fumarole deposits. Sulphur volcanoes are active on Jupiter's moon Io.
Tenderfoot hikers will be pleased to learn that this is the most easily accessible active volcano in the world, though some visitors may not consider "accessibility" to a live volcano an attribute particularly worth lauding.
There are three trails: Crater Trail is 750 meters (2,461 feet) long; it is a paved, direct path to the main crater. Botos Lake Trail runs off Crater trail, and it is about 1 km. (0.6 mi.) long, and winds through the forest to Botos Lake. The twenty or thirty minute hike ends at the world's most perfect spot for a picnic. Escalonia Trail (about 1 km.) starts at the picnic grounds. Just follow the signs.
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