“A proposal under consideration here called the Flussbad (‘river pool’) would clean up a filthy canal, part of the River Spree, that flows around the tourist-mobbed Museum Island. The plan would add new wetlands and some place the public can literally dive into. Despite detractors who picture Berlin’s cultural center being upstaged by the equivalent of one long, riotous water-filled bouncy castle, the idea, which has been around for a while, is gaining momentum.”