Moving water / moving people.
I like doing long exposures that have people in the frame largely because once you press that shutter you never know what will happen. I know what a waterfall will do over the span of 30 seconds but what a small group of hikers will do is anybody’s guess. Sometimes they move how you want them to, and sometimes not. They did not here, but that is fine. I can love the concept more than the result. And the result is still interesting, even if the motion seems a bit awkward.