How can I make people to breath under the ocean?

[submarino]

I love the ocean (i'm an mechanical engineer), i think that the sea is part of us as human beings. But my knowledge is not far enought to know how to make people to be under-seas because i'm wondering how they breath, and how to control the CO2 and the moisture, if those persons are in an closed system, like a vessel. I've reading the Mark's but i still have no answers. If any of you have any system or explanation i'll appreciate it because i'm very lost at this item.
Thanks.

 

[mbridger]

Co2 scrubber systems remove the CO2 by use of "soda sorb" and simple fridge systems remove the waterby condensation. Atmosphere control is extremely important for people breathing compressed gasses.