A mixture between a hostel and a novelty pension, the Hostelboat gives travelers the opportunity to sleep bobbing on the waves of the Spree a short distance from the East Side Gallery. There are 25 cabins organized by class and type of "comfort," and for quite a bit extra you can upgrade from a dormbed cabin with a porthole to a spacious, private room with windows. For the summer backpackers who can do without, there is perhaps no accommodation cheaper in Berlin than a pitched tent on the ship's upper deck.