Bookmarklets | MOVABLE TYPE Dubai is planning an underwater hotel that will cost up to half a billion to build. With about 220 rooms, the Hydropolis Hotel will entertain guests with underwater views, a half-submerged concert hall, snorkeling and of course a plastic surgery clinic. They're going to have some sort of marine biology lab too. Guests will get to the hotel by way of a train travelling through a 1/3-mile long plexiglass tube. Living with the fishes won't come cheap: rooms will cost up to $5500 a night. Reserve now for the planned 2006 opening.