I've not seen this brought up at the BBS [highly probable I just missed it!], but Ive got some pretty strong feelings about proper sunglasses for kayaking. I'll mention mine, but im interesred in other folks opinions...
Im striclty a polarized sunglasses wearer with regard to kayaking - or really anything to do with the water. Its the most natural way to really sea the oceans true color. Glasses that dont eliminate some or basically all of the sky glare on the water really only show what the surface is reflecting. I know this is a fairly obvious statement but it comes back to me everytime I go out to the real ocean - as opposed to long island sound. Off the coast of Rhode Island the ocean was this luminous glowing teal that just blew me away. Taking the glasses off just gave me the basic "same ol' same ol'" look of steely blue water, which is nice to be sure, but its a product of reflected sky. To really see the true ocean, polarized lenses are the only way to go. I know I make a fairly obvious argument, Im just so bent on it!!!
That said, the worst sunglasses are those that besides not being polarized have color absorbing tints. Blue Blockers for example are about as ocean unfreindly as you can get. Its literaly absorbing the best wavelengths that make up that funky teal. Next to that are those purple, pink or yellow lenses. Again these colors are absorbing the best parts of the scene. Purple kills the yellow that makes the teal - teal, pink kills the blue in the blue green, while yellow does the same tho to a different extent.
Thought I'd just pontificate.