Actually Colter Bay is about 45 miles, of beautiful scenery, from the south entrance to Yellowstone, about a one hour drive. If a person gets up pretty early they can have a full day in Yellowstone, one doing the upper loop and one doing the lower loop. Then, you can come back to see what you missed on the other two days. Generally, we do this once each time we go to Colter Bay for a week. We bring our boat, camp in the campground and fish. When we feel like it, we cruise up to Yellowstone to look at the features, saw three this August that we hadn't bothered to stop at before. Did it all in one day and got back to the trailer in time for a wonderful dinner as the sun was starting to go down. We usually get up to Grand Teton three times each summer, for about a week at a time. Best place in the world.