What Tim said about roll tops dry bags.
I’ve spent some serious money on ‘dry’ camera bags and been very let down, but the cheaper Lowpro Ranger pack I have with a couple dry bags has been great.
In the Ranger I have a dry sack lining the bottom padded section.
Normally it’s rolled down out of the way and the pack works like any other, but if it’s raining or I’m deep wading, I roll the top over the gear.
www.dsaphoto.com
A picture is thousand words that takes less than a second while a thousand words is a picture that takes a month.