With hundreds of shimmering cerulean pozas (pools) and streams in the middle of the Desierto Chihuahuense (Chihuahuan Desert), this 843-sq-km nature reserve is a surreal sight. Fed by more than 500 underground springs, it's a desert habitat of extraordinary biological diversity, often compared to the Galapagos Islands. It's home to over 70 endemic species, including three kinds of turtles and 11 kinds of fish, as well as primitive organisms called estromatolitos (stromatolites), which are linked to the creation of Earth's oxygen-rich atmosphere.
Some pools and the nearby river have been set aside for recreational activities, including swimming. Much of the area is off-limits to the public, as it's being studied by researchers from organizations as diverse as NASA and UNAM.
The main gateway to the park is Poza Azul. Here you'll find a visitor center, with displays in Spanish and English on the area's flora and fauna. The Poza Las Tortugas, a good turtle-spotting pool, is right behind here, while 1.5km further back is the aptly named Poza Azul (Blue Pond), one of the reserve’s most photographed sites. Licensed guides can be hired here (there's no fee, you'll just pay admission for the individual sites). In town the tourist information office has a list of recommended guides, all of which can provide transport if you don't have a car.
Located about 9km southwest of town.