If you put them 100 feet underground they will nicely double as underground shelters for when the zombie apocalypse hits.

How is the tube heated and cooled? Living without vertical and horizontal walls, ceilings and floors can be very disorienting. The acoustics are probably lousy. Looks totally miserable to me.

I think it is a neat room but I don't consider it a house.

Bury them underground to make good bomb shelters--Japan will need them soon which NK is getting ready for WWIII.

Is anyone else seeing "prison cell" with modified furniture, etc?

Like -snowflake0446- my thoughts were 'prison cell,' why would anyone choose to live in one? Maybe if you were homeless, then one of these would be better than the street, as long as you were not claustrophobic, or dont mind living in a virtual fish tank.

Not the mot efficient use of space , a square shape would be more efficient and liveable from a users point of view. But great for ex-submariners!

Well, if you have some concrete water pipes laying around might as well...

Could be combined with a larger cylindrical water tank type structure to add volume. A very easy shape to manufacture and very strong. I have lived in small boats over a number of years and found no problem with the tunnel shape.

The hexagon, 6 sided, is the most efficient shape for construction of this type. The space between the tubes as shown could be used for wiring and utility access.