They live in a sealed chamber where the pressure is slowly adjusted over days or weeks then they can go out in a suit and do the job. The chamber can be on the surface and lowered, or it can be permanently underwater. Similar time is required to return to normal life.
It's often said that we know less about the depths of the ocean than we do about space.
phavoc wrote: ↑Thu Jun 06, 2019 1:35 pmSpace is the most deadly place humans can be. There is no air, heat, or gravity. Submarines are a close analogy, but also they are not. Today the only people who spend long terms underwater are military personnel. Civilian submarines are designed for very short-term use. Even submarines are pretty well compartmentalized, though within each compartment there is no attempt to build redundancy into the compartment itself since it could not withstand the pressure.