An innovative mission on the Welsh border, funded by an anonymous private investor, has begun work to create a ‘permanent human settlement’ under the sea

Down an easy-to-miss turnoff on the A48 just outside Chepstow on the Welsh border, the gentle rumble of trucks, cranes and people at work mixes with birdsong in what is an otherwise peaceful rural setting. It is a crisp and sunny winter morning when I visit and, at first glance, the site appears to be little more than prefab containers and a car park. Yet, behind the scenes a group of men and women with expertise in diving, marine biology, technology, finance, construction and manufacturing are building something extraordinary. They have come together with a single mission statement: to make humans aquatic.

Their project is called Deep (not The Deep) and the site was chosen after a global search for the perfect location to build and test underwater accommodation, which the project founders say will enable them to establish a “permanent human presence” under the sea from 2027.

Phil Short, research diving and training lead at Deep, outside the full-scale replica of the subsea sentinel habitat under construction at a site on the Welsh border. Photograph: Mark Griffiths/the Observer