There are many canyons formed by the Rio Grande in Big Bend. One of the largest and most impressive is the Santa Elena Canyon on the west side of the national park. The hike starts off in a little wooded area with small trees and grass that have grown on the banks of the Rio Grande.
Afterwards you hop down onto the little beach and cross the Terlingua Creek via a bridge made of small sticks by hikers that don’t want their shoes wet. From here it starts a steep climb of switchbacks up the canyon wall and then peaks and slowly dwindles downward to the same level as the river again. There are also a couple signs describing the plant life growing on the canyon walls.
The trail goes squished between the canyon wall and the river for a little but before dead ending at a large boulder. The canyon is quiet and echoes a lot and despite being a popular hike it feels very peaceful.
The parking lot fills up very quickly so you might want to get there early in the day if you want to not stress about all the cars but I think the best time to visit is midday when the sun is above the canyon and does not cast too many shadows.
Thanks! – Josh