MonsterCrit said:
I've often said. before they can build a base on the moon, they need to build a self-sustaining colony on the ocean floor. At least a thousand feet down. Yeah I know space and the ocean are two fairly different environments but the methods and problems are comprable. You have to creat a sealed, air tight, pressurized enclosure capoable of withstanding a variety of stresses. Find a way to generate, store and recycle oxygen water and food for the long term, and keep people from going batshit insane for the same period.
It'll be cheaper, easier and less harmful than trying to develop the techniques in space.. for starters there's a whole slew of problems caused be low-micro gravity. Weakening of the bones, heart, muscles and blood vessels for starters.. Then there's the bacteria. Yeah apparently in low gravity, Virii fungi and bacteria basically go super saiyan.. while the human immune system conversely gets a little weaker.
Actually you're very much off on your estimations and assumptions here.
The bottom of the sea is a far more hostile environment than space is. The great pressure under the sea makes it a significantly harder engineering challenge to build a liveable environment down there. Space is -14.7 psi pressure compared to Earth sea level. Pressure on Mars is slightly above that. Five miles under the sea is 11,800 psi pressure.
It almost can't be done. And even if it could it'd likely be exponentially more expensive and unbelievably dangerous (because you flat out could not have any flaws in design at all or the entire thing would instantly implode).
Sources in case you want to read a bit more:
http://www.forbes.com/sites/quora/2013/01/31/why-dont-we-spend-more-on-exploring-the-oceans-rather-than-on-space-exploration/
http://www.quora.com/Given-the-actual-space-station-ISS-would-it-be-cheaper-to-build-the-equivalent-at-3-4-5-miles-deep-underwater-Why