Rincón de la Vieja stands 1916 metres above sea level, and its summit is the highest point in Rincón de la Vieja Volcano National Park. It erupted most recently in February 1998. The volcano has a large number of fumaroles and hot springs on its slopes.
Rincón de la Vieja is a ridge-shaped massif, with several volcanic vents lying along a northwest-southeast axis. Several craters and peaks exist, with Santa María peak being the highest at 1916m above sea level. Von Seebach peak, 1895m above sea level, has been the site of most historical eruptions.
Little is known about Rincón de la Vieja's early eruptive history. It lies within a larger caldera, which indicates that a very large eruption probably occurred thousands of years ago. Analysis of nearby pyroclastic flow deposits shows that they were erupted in a moderately large eruption about 3500 years ago, and the first recorded eruption of the volcano took place in 1765.
Since then, many minor eruptions have occurred, the most recent in 1998. They have mostly occurred at a crater near Von Seebach peak, and have been characterised by strombolian and vulcanian activity in which eruptions are confined to the crater, and ash is erupted to moderate heights. The active crater is currently filled with a hot, acidic crater lake .
Large number of hot pools and areas of bubbling mud are found in two areas on the slopes of the volcano, indicating substantial reserves of geothermal energy. Investigations have been carried out into the feasibility of tapping these reserves, and the volcano is estimated to have a generating potential of 140 megawatts. However, as the area is protected within a national park, drilling has so far been limited to test wells. Further drilling will require approval after studies of the likely environmental impact.
Hikers may climb to the crater and guides experienced in wildlife, birdwatching, geology and other interests are available. Several lodges, resorts and hotels in the area offer hiking, forest canopy tours, horseback riding, river-rafting, all-terrain-vehicle riding and wall-climbing. The area is cooler than the Guanacaste beaches.