Gregory Natural Bridge, which once spanned the creek in Fiftymile Canyon, is now underneath the waters of Lake Powell. It had a span of 127 feet. The photo above (from the upstream side) was taken in 1968, one year before inundation, when the rising waters of Lake Powell meant that you could no longer walk under the span but would need a boat. Note the person on the rock ledge behind the span. The photo below was taken later from the downstream side when one could still boat under the span. The bottom photo was taken in 1969 just before the opening completely disappeared under the waters of Lake Powell when the water level reached 3552 feet (the top of the span is 110 feet higher). Stan was snapping photos trying to capture the event, when suddenly a boat appeared and one lone unidentified swimmer probably became the last person to breathe fresh air within the opening of Gregory Natural Bridge. In the photo you can see this person in the sunlit area under the span, reaching up to touch the rock.