The Poás Volcano, (Spanish: Volcán Poás), is an active stratovolcano in central Costa Rica. It has erupted 39 times since 1828.

There are two crater lakes near the summit. The northern lake is known as the Laguna Caliente ("hot lagoon") and is located at a height of 2,300 m in a crater approximately 1.7 km wide and 290–300 m deep. It is one of the world's most acidic lakes. The acidity varies after rain and changes in volcanic activity, sometimes reaching a pH of almost 0; consequently, it supports little or no aquatic life. The bottom of this lake is covered with a layer of liquid sulphur. Acid gases create acid rain and acid fog, causing damage to surrounding ecosystems and often irritation of eyes and lungs.

Lake Botos, the southern lake, fills an inactive crater, which last erupted in 7500 BC. It is cold and clear, and is surrounded by a cloud forest located within the Poás Volcano National Park.

Poás was near the epicenter of a 6.1-magnitude earthquake in January 2009 that killed at least forty people and affected Fraijanes, Vara Blanca, Cinchona (the most affected area), the capital San José, and the Central Valley region of Costa Rica.