Big Bend Ranch State Park.

Spanning over 311,000 acres of Chihuahuan Desert, Big Bend Ranch is the largest and most rugged state park in Texas. It is defined by its sheer isolation, offering a starker, more primitive experience than its neighboring National Park. The landscape is a mix of volcanic mountains, steep canyons, and the winding Rio Grande, accessible via the scenic FM 170. Adventure here is self-reliant, centered on 238 miles of multiuse trails for hiking and mountain biking, plus unmaintained dirt roads suited for high-clearance vehicles. Notable features include the bizarre rock formations of the Hoodoos Trail and the "hanging gardens" of Colorado Canyon. As a designated International Dark Sky Park, it offers world-class stargazing, while the terrain remains home to longhorn cattle and feral burros.