We look at five habitats underwater that show it is possible to live submerged beneath the waves.
1. Hydropolis Hotel, Dubai

Designed by Joachim Hauser, this futuristic hotel is currently being built 20m below the surface of the Persian Gulf, just off the coast of Dubai. Touted to be the world's first underwater luxury hotel, Hydropolis will include a marine biology research center but it's doubtful whether it will be oozing eco credentials.

The logistics of these underwater habitats are intriguing; for one, where is the waste diverted to? Imagine gazing out at the underwater world, mesmerized by the vision beyond, amazed and in awe of the creation, when something floats by your panoramic window… and it's not a fish.

If it succeeds without ruining everything around it, as many predict, it could be a blueprint for sustainable designers and architects for the future.