Review on SE Waterproof Resealable Pouch: Ultimate Protection with Hook and Loop Closure (7” x 9”) - TP128 by Daniel Mandal

I haven't tested this fully submerged but I suspect it will hold almost all water successfully. Almost all. I think as long as it's a fast dive - like if you get knocked off your feet crossing a creek and dunk your pack in the water before you put your feet under you - you'll be fine. But if you didn't get back on your feet and stayed in the water for a while, the water most likely got in, although it's probably not enough to be a problem (unless you're trying to protect the electronics, in which case putting it in the freezer). pocket and put it in this pocket should be fine). The extra zipper in the shape of a freezer bag would probably make it almost perfectly waterproof.