Ocean Spiral

Shimizu Corp plans an underwater city called Ocean Spiral powered by the seabed. Shimizu says Ocean Spiral will "capitalise on the infinite possibilities of the deep sea" to accommodate human life, as rising sea levels threaten the survival of island communities.

The ambitious structure will be divided into three sections. A floating sphere with a diameter of 500 metres, located just beneath the surface of the sea, will house business and residential zones and hotels. The pod will be connected to a 15km-long spiral path that winds its way to the ocean floor 3-4km below the surface. There, scientists will explore ways to excavate energy resources from the seabed.

Ultimately, Shimizu envisages an eco-friendly underwater city sustained by energy brought up from an “earth factory” on the ocean floor. The factory will use micro-organisms to turn carbon dioxide into methane, while power generators located along the ocean spiral will use differences in seawater temperatures to create additional energy – a process known as ocean thermal energy conversion. Desalinated water produced using hydraulic pressure will be pumped into the residential pod.

The idea of creating communities in the sea resonates in Japan, where land-based communities are at risk from large earthquakes and tsunamis.

Among Shimizu’s other ambitious projects are a lunar base, a hotel in space and floating botanical cities.

Future of Oceanic Cities
Multiple Spirals could be connected by underwater transparent tunnels in which vactrains move passengers from one underwater city to another. Not only could the tunnels be transparent, but so to could be the domes, making for spectacular sight-seeing. People living in these underwater cities or taking a ride on the maglev train through those transparent tunnels could witness oceanic lifeforms and an array of amazing architecture.