Lake Powell is a reservoir on the Colorado River, straddling the border between Utah and Arizona (most of it, along with Rainbow Bridge, is in Utah). It is the second largest man-made reservoir in the … see full wiki
The Glen Canyon Recreational Areas and Lake Powell are simply awesome from the air. It was on a day excursion from Las Vegas to Monument Valley that I was greeted with the most incredible sights I've ever had the fortune to see on a flight (the other being an hour flight around Mt. Everest). Not many have seen the sights from the top but if you do get a chance, I highly recommend it to you. It's simply breathtaking!