Santa Elena Canyon, Natural canyon at Rio Grande border between Brewster County, United States and Chihuahua, Mexico.

Santa Elena Canyon is a narrow gorge where the Río Grande cuts through tall limestone cliffs, forming a dramatic passage that marks the border between Texas and Mexico. The river has carved its way between these rock walls, creating one of the most striking sections within Big Bend National Park.

The canyon formed between 60 and 130 million years ago when flowing water carved through limestone that once lay beneath an ancient sea. Over time, the Río Grande became the natural boundary marking the division between two nations.

The canyon marks the Rio Grande border, with Big Bend National Park established on the Texas side in 1944. A joint park with Mexico was planned, but the Mexican side only became the Santa Elena Canyon and Maderas del Carmen flora and fauna protection areas in 1994. The Santa Elena Canyon Trail on the US side leads to the river's edge.

The Santa Elena Canyon Trail starts at the end of the paved Ross Maxwell Scenic Drive on the park's west side and runs about 1.7 miles round trip, crossing Terlingua Creek before climbing a short set of switchbacks. The creek crossing can be muddy or impassable after rain, and the trail's far end is a dead end at the river. Summer daytime temperatures here often exceed 38 °C, so plan walks for morning.

The canyon marks the international border: the Rio Grande runs along the Texas–Chihuahua line, with Big Bend National Park on the US bank and Mexico's Santa Elena Canyon flora and fauna protection area on the other. The Santa Elena Canyon Trail on the Texas side leads to a river overlook.