This very active, 90.52-sq-km complex peaks at Volcán Telica (1061m), the twin craters of which are a mere 30km north of León. Also called the ‘Volcano of León,’ Telica is active in four- to five-year cycles; the last really big eruption was in 1765. Most eruptions these days involve gases and a few pyroclastic belches. It's easy to combine the four-hour hike to the impressively smoking crater with visiting the boiling mud of San Jacinto. Camping overnight is popular, too.
There are several ‘extinct’ cones around the base, including Cerro Agüero (744m), Loma Los Portillos (721m) and Volcán Rota (832m), which has constant fumaroles.