Before astronauts go out on a normal spacewalk, they simulate the procedures many times in a huge swimming pool called the Neutral Buoyancy Laboratory in Houston. This not only lets them get used to the equipment, but also where things are located on the station and how weird it is to move around in a spacesuit. (You ever try doing a delicate job in hockey gloves while floating around? Yeah, that's tough.)
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NASA first started using this technique in the 1960s when it was figuring out to how move astronauts around safely outside; at the time, few handholds were hampering people in their tasks, causing overheating and frustration. While the pool is huge, at 202 feet long, 102 feet wide and 40 feet deep, it's too small to hold a full-size model of the International Space Station.