Dart is in a National Park. (Vicki: You’ve got this one!)
We drove along the Colorado River yesterday and there are huge red cliffs on either side of the river. The cliffs are slightly tilted so you have the illusion of going down hill (but you are not), so the river appears to be flowing up hill.
We ventured on some back roads and some of them were pretty rough. There are several areas with trails for off road vehicles. One particular area seems to be popular where the trails are over slickrock.