Correct. The article was in a consumer electronics magazine (i.e. no great detail), but apparently the driver was made watertight and submerged in the waterchamber. Water is a much better medium for long-wavelength transmission, and thus acted as a LF booster (ever noticed how well LF propagates through water?). The sub was tuned by the amount of water inside and adding additives to the water to change the viscosity. Should the technology be used commercially I can already see how "snakeoil" companies would start selling magic oils and liquids for superior sound!