Shoes are definitely important. We were at Garner State Park in Texas, hiking up one of the trails there, and on the way down the other side, we saw a group heading up to see Crystal Cave. It was quite a rough downhill climb for me and my wife, but on the way up, this group of people had everything from tennis shoes (okay), to sandals (pretty rough), to flip-flops (pretty stupid). One girl asked how much further it was. I told her "in those flip-flops, you'll wish you hadn't come!". It was only about another couple of hundred yards, but it was very rocky with drainage ruts and tree roots everywhere. Crazy people!