I have a MarCum underwater viewing system. I use it for ice fishing (sometimes) and when I'm drifting for perch on Lake Michigan. I have 2 complaints which are sort of contradictory to each other. When drifting for Perch, I'm generally in water deeper than 50 feet. The camera cable is 50 feet long. Wish it was longer. When I use it ice fishing, the cable gets stiff and very difficult to maneuver the camera by trying to twist the cable. So you have to let out more cable so you can twist it. The more cable you let out so you can twist the camera the more cumbersome it becomes. My solution to this would be to use a cable with a flexible cover like used on a transducer. MarCum used to make a system where the camera panned 360 degrees and was controlled on the control panel. It also featured a compass so you would know which way you were looking. I believe they have been bought out and that camera system is no longer offered.
Oh, Lake Michigan has crystal clear water and I can see a good 20 feet with the camera (and see Perch) The ice fishing is done on more murky waters and 3-4 feet is about average. If you turn down the lights you can actually see further (sort of like the highbeams in the fog theory)