The Reventazón River or Rio Reventazón (Spanish pronunciation: [reβentaˈson]), is a river in Costa Rica which forms part of the Reventazón-Parismina drainage basin, it is 145 km long and flows into the Caribbean sea. It rises in Meseta Central and flows through the Orosí, Reventazón and Turrialba Valleys. After reaching the Caribbean coastal plains it joins the Parismina River and forms what is called the Reventazón-Parismina.
In its upper segments, the Reventazón River is the source of 25% of the drinking water of Costa Rica's largest metropolitan area centered on San Jose. The river is very important for power generation. Two reservoirs in the river, Lake Cachí (100.8 MW) and Angostura (177MW) are used for generating a significant share of Costa Rica's electricity. The dam for a third reservoir, Reventazón (305MW), is currently under construction and expected to be finished in 2016. The river is also important for tourism, specially for whitewater rafting.