The 4.7 mile turn in is a bit sketchy for your first time in there. It could be a mud pit if it's been raining, but there are some nice spots that way. BUT the 6.4 turn (by the antennas) is definitely the main entrance. Yes, turning right at the Y (per Blake) has closer spots, but generally closer means more crowded. Left goes for quite a while and has some pretty sweet spots. But don't go that way if it's wet. Unless you like to slip and slide. Expect wind (and I mean WIND) either way you go. It's South Dakota and you are exposed on the side of a cliff.