Double Arch is the third largest arch in the park, with a larger span 144 feet wide by 112 feet high and a smaller opening 67 feet wide by 86 feet high. At Double Arch, three major openings are enlarging side by side, and they all began as one pothole. Pothole arches start as depressions near a cliff face, where pools of water collect and slowly deepen the pothole. Over time, water seeps through to the cliff face, forming an alcove. Eventually, the enlarging pothole meets the roof of the expanding alcove, creating an opening, and the arch matures as erosion continues.