Swimming with the fish and turtles in this sublime stretch of slow-flowing blue water amid the desert landscape of the Cuatrociénegas nature reserve is a surreal, revitalizing experience. There are palapas (thatched shelters), picnic tables and even grills. Several sets of ladders and steps lead visitors into the water (or do as the kids do and cannonball in). Last visitors admitted at 5pm.
From town, look for the turnoff just before the Poza Azul Visitor Center.