Best place to buy marine plywood in Ontario?

[Chotu]

I second Noah’s. I’ve bought a ton of stuff from them (literally) and it was always best quality and reasonable prices.

Boulter Ply if in the States.

[Leee]

Exterior grade plywood contains voids in each ply layer and utilizes poorer grades of veneers, it is therefor unsuitable for marine use. Spec's for marine ply:

1. The Glue MUST be waterproof
2. Voids are to be avoided
3. Face and inside veneers have to be good