Transparent Canoe

If you're into glass-bottom boats, then this is right up your street. Hammacher Schlemmer are selling a transparent plastic canoe that lets you look through the hull's bottom at the fish looking up at your bottom.

I would not recommend using this in one of those tropical places where the water is so clear that you can see straight down for a thousand feet unless you want to be history's first case of sea-level acrophobia.