Spectacular designs show world's first 'underwater skyscraper' which would be capable of accommodating 20,000 people (7)

Air is renewed naturally by convection through wind chimneys found in the tower or by an oxygen station.

And Mr Callebaut says food comes from coral reefs, farming fields and fishing.

He said it is possible to farm fruit and vegetables inside the eco-villages as well as fishing in the ocean.

Mr Callebaut also suggests that these eco-villages, which are 500 metres wide and have 250 floors, are spread across the world's major oceans.

Each eco-village costs ￡1,430 every square metre to build.

The top of the buildings are above the surface of the water and they spiral down up to 1,000 metres.