Northwest of the tiny settlement of Tomás de Berlanga lies the massive Volcán Sierra Negra (1490m), which last erupted in late 2005. An 8km trail leads around the east side of the volcano. It’s possible to walk all the way around the caldera, but the trail peters out.
Galápagos hawks, short-eared owls, finches and flycatchers are among the birds commonly seen on this trip. The summit is often foggy (especially during the colder, drier garúa season, which extends from June to December) and it is easy to get lost. There are spectacular views from nearby Volcán Chico, a subcrater where you can see fumaroles. Several agencies in towns offer all-day tours (per person $35). These include transport up to the volcano, followed by an 11km walk. Bring a rain jacket, water and snacks (a sack lunch is provided).
Make sure you go only in a closed vehicle (and wear your seat belt); do not go in an open-sided chiva. A tragic accident in 2014 left several tourists on this outing gravely injured, when the driver of their chiva lost control coming down the mountain.