OK so I want a Nikonos.
It will serve mostly as a snapshot camera when I am near/in the water or in bad weather. I do not intend on using this for scuba diving or any serious underwater photography. I like pictures of people, mostly, and so it will be in shallow waters or in relatively clear swimming pools.
I've narrowed it down to the III or the V. Well they both seem popular, reliable, and not too expensive but what it comes down to is the importance of the light meter and the nausance of the battery (well, it is a nausance to me). I generally prefer all mechanical cameras because I use an incident meter or sunny 16.
So how difficult is guess exposure underwater? I don't have any under experience and there don't seem to be many guidelines, and I can see why. I'm totally comfortable with sunny 16 (in air) and so I'm wondering if I can simply add a stop in a swimming pool water and two stops in ocean water or something simple like that.