Here's the NBL(neutral buoyancy lab), where they simulate the microgravity environment for EVA's. This pool is huge, lemme tell ya. It is the largest indoor pool in the world, with about 6.2 million gallons of water heated to about 86 degrees. In this picture, you can see the Space Station side of the pool. What you see there is the Node 1 module and the U.S. Lab module, with the S0 Truss segment running along top.