So..years ago...a decade or more, I used buy "Marine grade plywood" in 3/8" sheets and half sheets at Home Depot. It was different from "pressure treated" in that the glue used in the manufacturing process was more water poof and stronger than that used in the PT stuff. I used to use it for transom repairs, building live wells, etc etc. (I know some guys in FL who have built 20' jon boats with it.)
I can't find it in Anchorage. The guys at Home Depot and Lowe's have never heard of it. Did they stop making it? Was this stuff ever available up here? Does anyone know where I can buy some locally?