Copenhagen's harbour was too polluted to swim in until 2002, when the first Havnebadet opened at Islands Brygge and turned an industrial channel into a public pool. That single act of cleaning changed how the city is read from the water. Two decades later the same stretch is the departure point for Copenhagen electric boat rental, and the quays that once received coal and grain now hold sunbathers, joggers and moored picnic boats. The water is no longer a working edge. It is the city's widest public square, and the least crowded one. The canal system itself is deliberate. Christian IV ordered Christianshavn built on reclaimed ground from 1618, with straight canals cut between ramparts to serve Dutch-style merchant plots. Frederiksholms Kanal followed later that century. Nyhavn was dug by Swedish prisoners of war between 1670 and 1673 as a cargo channel running directly to Kongens Nytorv. None of it was designed for leisure. Yet the geometry survives almost intact, which is why a Copenhagen electric boat rental tour reads as a tour of urban planning history: warehouses at Gammel Dok, the ochre facade of Eigtveds Pakhus, the yellow ranks of Wilders Plads, and the spiral timber spire of Vor Frelsers Kirke turning above the rooftops. Modern Copenhagen has answered the old warehouses with glass. The Black Diamond extension to the Royal Danish Library opened in 1999 in black granite. Henning Larsen's Opera House followed in 2005 across the water at Dokøen. Olafur Eliasson's Cirkelbroen, five linked circular platforms, opened in 2015; Inderhavnsbroen, the sliding pedestrian bridge, in 2016. Copenhill's ski slope over an incinerator completed the skyline in 2017. Copenhagen electric boat rental tours pass beneath most of these at a walking pace and without engine noise, because the boats run on batteries rather than diesel. Each hull carries a round table instead of rows of seats. The design brief was a floating dining room, not a ferry. What makes the harbour unusual is its permissions. Denmark allows small low-powered electric craft on the inner harbour and the Christianshavn canals without a boat licence, which is why a self-drive fleet exists here at all. Few European capitals extend the same trust to visitors. The result is a form of city access that belongs to the passenger rather than the guide: a Copenhagen electric boat rental puts the tiller in a visitor's hand and leaves the route largely open, from Bryggebroen in the south to the quiet dead end of Trangraven. The harbour reads differently at that height. Facades built to be seen from ships are seen from ships again.