It WOULD protect against the coming rising sea levels. That would be awesome. Humans - 1, Global Warming - 0 lol. (Just to clarify, I hope global warming DOES get the better of us. It'll teach us for being such douchebags).
I wasn't aware that staying alive was douchebag behaviour. Damn me for having the will to live, I'm such an asshole!
Yeah I wouldn't dare step foot in such a city. All it would take would be one big tsunami and you'd be buggered.