Wow, I'm amazed at these replies. The first thing I notice is that no one used the word "boots." I don't know much about ultralight backpacking---I'm trying to go light rather than ultralight. I'm assuming that most of you avoid boots? I know there are ecological reasons to not wear boots, especially ones with a heavy tread.

I feel I must wear boots because I have some extra body weight and one bad ankle and need the support of boots. On my last trip there were at least 10 stream crossings. I actually timed myself and it took me about 10 minutes to take off my pack, change from boots into crocs, cross the stream, dry my feet, and put my socks and boots back on. That means that at least one hour per day was spent just changing footwear! That bugged me but I couldn't figure out any other way to do it.

I also found that constantly taking the pack off and putting it back on for stream crossings consumed quite a bit of energy. As an older person I can't afford to squander any energy. That trip convinced me to abandon my 5-lb 8-oz. Gregory Baltoro and get a pack I can actually carry.

For the moment I don't have any solutions, especially in the fall when getting wet and staying wet is not an option. To the OP: Crocs are very light, easy to clp to your pack, and a joy around camp after a long day on the trail.