We wanted to stay overnight in YNP in late October and found out that most of the hotels were already closed and the only campgrounds open were Mammoth, which is open year-round and Lewis Lake, which was open until 11/4. We had no trouble finding a spot in the late afternoon but because it was the only camping available , and it is YNP, it filled up fast! Nice but tiny sites, pretty trees and a separate area for tenters . This campground was very quiet. It was also very clean considering it had hard use all summer. Every site has a little tent pad, a table, and a fire pit. The rangers had turned off the water so there was no fee either! The boat ramp at Lewis Lake was perfect and the lake was glassy so we had excellent canoeing. This review is heavily determined by the time of year, and the excellent weather we enjoyed. But it gives a different twist to camping in Yellowstone.