A different sort of dry bag Im currently making is a under deck bag. Its close in design to the one in the below link but made from waterproof canvas and with a roll up and buckled opening like a dry bag. I like the idea of being able to store food, binoculars, clothing etc in in an easily accessable place without having to have each item in waterproof bags.

Because I have a plastic kayak it is held in place by a framework of strips of corrogated plastic attached to the underside of the deck fittings (no need to drill holes in the kayak).

It is easily removable, and I hope to be able to attach shoulder straps so I can use it as a day pack.