Not many people know about this hike, which is especially interesting given the beautiful oasis payoff at the end.
Head south on the Ross Maxwell Scenic Drive in Big Bend. Just after mile marker 3, you will see signs for the Sam Nail Ranch overlook, and a small opening in the scrub brush will appear on your left... but go slow, it's easy to miss!
Turn left down the dirt road. Follow it for about a mile or two until you reach a remote parking area in the desert. The road is not terrible, but be careful. Ruts can be deep and there can be large rocks you may need to move out of the way. After parking, head further down the road until you see a barricade. Keep walking past the barricade down to Oak Spring split and take the trail right up the hill, not to the left. The left trail will take you all the way up to the Chisos Basin via the Window trail.
The Hike:
Cattail Falls Coordinates: 29.2731, -103.3355
The Cattail Falls trail is only about 1.5 miles or so up into a canyon. When you get through the desert portion of the hike and begin to reach the heavier vegetation, be on the lookout for black bear. They frequent this area, so make noise as you hike.
The trail will go over large boulders toward the end and finish at the pool at the foot of Cattail Falls! I have hiked there dozens of times, and rarely see more than a trickle from the Falls. But if you catch it after a heavy spring rain, you'll be impressed, and it might even be enough for you to take a dip! Be careful when exploring the area as there is quite a bit of poison oak.
Enjoy! It is a special place that only the seasoned Big Bend explorers know :)