when is low vis a problem and why? what is the fear? I have been diving the local mud pit a lot lately for DM course and there are times when I say to myself, wow this 6ft vis is great today, and then there are times when I feel like my underwater world is very small and long for the open ocean. last weekend we were cleaning the trash from the lake and I was looking for trash or a numbered golf ball in about zero vis, seemed ok but I was a little nervous that I would stick my reg in the mud and gunk it up, I guess the only fear at that would be a free flow and end of the dive. when I did my wreck course we went into a wreck with a line and about 3ft of vis, seemed a lot tight in there and I did not want to hang about. I had a line and was somewhat comforted by that but if I had gotten tied up in something I might have had to take quite a few calming breaths. so what about low vis bothers you? Sharks? alligators? accidentally swimming into a cave? bumping your head?