Very true. Polarization can be in any orientation. I was simplifying for sunglasses, as that's what we're discussing here. Indeed there are water specific lenses, but any polarized is going to be better on water than non polarized.
As another aside, don't wear polarized shades when wearing a full face motorcycle helmets for the reasons ronin stated. A lot of guys don't like them for skiing/snowboarding either, as they can make it harder to spot ice, as there is no classic glare signature.
Looks like cutting out too much glare can be bad thing in some ways. I don't ski but good to know in case I ever decide to try. As for full face helmet, it's the computer effect that's gonna be a problem I suppose?