Japanese designers are preparing for rising sea levels – by making plans for a huge floating city. Developer N-Ark says ‘Dogen City’ would provide a self-sufficient habitat for 40,000 people, a quarter of which would be permanent residents. The city is made up of three main parts – the first is an outer ring that contains the main living areas and facilities for water, sewage and energy. Inside the ring there are floating buildings that can move freely around, with renderings showing boats ferrying residents around the city. Below the water’s surface, meanwhile, there is an undersea data centre and medical research facilities. The outer frame of the city is shaped like the body of a ship, which helps it to act as a defence against tsunamis, according to the designers.