Abstract: A liquid enriched with a high concentration of free gas, in particular, water enriched with free oxygen, is produced by mixing the gas and liquid in an overpressurized system to form a mixture and then abruptly reducing the pressure of the mixture. Alternatively, the pressure reduction may be accomplished using a series of pressure reduction containers which sequentially reduce the pressure on the gas-enriched liquid in a slow incremental fashion, thereby allowing a high concentration of free gas to be maintained within the liquid phase.