Former astronaut Michael Foale had an interesting observation. When he was aboard the ISS, he talked about a flight to Mars. He said that one of the biggest things one would have to get over would be the total blackness you would see for months on end. Once you get beyond the orbit of the Moon, there would be nothing to see out the windows except total unrelenting blackness. That’s not a proble in Earth or lunar orbit. The blues and ochres of Earth and the tans and grays of the Moon is great to look at.
So, you might as well et used to looking at the interior of the ship. It’s the only place where variations of color would affect your mood. I’ve never served aboard a submarine, but I would imagine having some variations of colors is essential on long cruises. Otherwise, you’d go out of your gourd. I know I would. If there are any submariners out there, what are you thoughts.