Neutral buoyancy diver maintains neutral buoyancy by continuous correction, usually by controlled breathing, as neutral buoyancy is an unstable condition for a compressible object in a liquid. The mathematician Archimedes discovered much of how buoyancy works more than 2000 years ago. In his research, Archimedes discovered that an object is buoyed up by a force equal to the weight of the water displaced by the object. In other words, an inflatable boat that displaces 100 pounds (45 kilograms) of water is buoyed up by that same weight of support. An object that floats in the water is known as being "positively" buoyant.
Neutral Buoyancy Simulator that neutral buoyancy exercises could help with EVA planning while he was reviewing film of the Gemini 4 EVA. He and Charles D. Stocks pursued the idea with a couple of NASA scuba suits and an diameter, deep pool which had been previously used for forming metal parts explosively. November 1965 tests included removal of the ST-124 and a J-2 engine propellant utilization valve - early steps in a nascent Skylab mission, then called S-IVB orbital workshop. After the utility of the technique had been demonstrated, in January 1966, workers repurposed a larger explosive forming tank for neutral buoyancy testing.