Tin Valley was a wonderful home base for exploring Big Bend and the surrounding area. It's about 45 minutes away from the entrance of the park (and the small town directly outside it, complete with gas station, a small but surprisingly well equipped grocery store, and a few restaurants). GPS will probably cut out on you about half an hour away from the site, but finding it is fairly straightforward. Every direction Google Maps gives you is accurate except the last step, which is to turn left instead of continuing straight at the end of Marathon. Tin Valley helpfully posted not just one, but two, signs to show you the right way at this junction. So, follow signs for Terlingua Ranch Lodge to get onto the paved side street from the main road, drive about 13 miles to the sign for Marathon (it's right before the pavement ends, and there's a generous loop at the end of the dirt path, so if you have a big rig and miss it, you'll just be redirected to the same road anyway, no biggie). This loop, which is about 3 miles from Marathon Road, is where the lodge is. I would recommend getting a key for the pool between office hours of 9-5 at the lodge so if you get back from hiking sweaty and in need of some cool water at 7 or 8 pm, you can get in. I would also recommend downloading a map of the area (or going the old-fashioned route) so you don't miss the turn off the main road like I did and then not have cell signal for a long stretch to get you back to the RV park. There is a bathroom and shower at Tin Valley (no extra charge), which is fairly spread out and quiet, in the shadow of a large hill, and which has wonderful desert views. I only had the barest trace of a signal near the bathroom/main house, so be prepared to disconnect a bit. The RV sites have 20/30/50 amp connections and are all pull-through. There is potable water at the site. I did some searching before I went to Big Bend, and this was the best site I could find that had access to a pool, showers, bathrooms, and electricity with amazing views and a great price. This is the place I plan to stay the next time I go to Big Bend. Thanks Tin Valley!