Astronaut Greg Harbaugh (here, with Steve Smith, training for a Hubble Space Telescope servicing mission in 1995) has logged 818 hours in space, including more than 18 hours of EVA. Of his underwater training experience, he said in a January 2009 interview, “The challenge is to strike a harmonious balance between what the suit wants to do, and what you need to do to get the job done. Sometimes you need to be upside down, head down, you need to be right side up, on your back, on your stomach—for somebody doing it right out of the starting gate, no experience doing that sort of thing before, it can be incredibly frustrating. You’re in this really ungainly, uncomfortable inflatable thing with these hard metal rings that can give you rubbing points. Your hands can get sore, your shoulders can get sore—overall, it’s not a very pleasant experience.
“But by the end of my training, when I got ready to do Hubble, by that time the suit fit like a second skin. You get so comfortable that you forget it’s there. After hundreds of hours in the water tanks, I really was very comfortable. And that, of course, is the whole goal, and makes you ready to do it on orbit, for real.”