
So this year the Logistics Support Battalion Group (me) did a bit of a ferret around, and we have gone for Toughprint
http://www.toughprint.com/
We even did some practical tests, like putting a printed sheet into a plastic milk bottle half filled with salty water, and then leaving the bottle in the car boot for a couple of days as we drove about 120 miles.
The paper came out with the printed map as good as when it went in - perfectly useable, flattened out and dried easily with a paper towel.
I'd recommend this product if you wanted to have a small (A4 or A3) chart of an area when you are zipping around in a rubber dinghy or buzzer. You can write on it with pencil or biro (though the latter can smudge when the paper is scrunched up, and there's a proper waterproof pen available too)
Usual disclaimer - no commercial relationship; satisfied customer only.