An experimental investigation of the effect of hydrostatic pressure on cavitation erosion is described. A focusing acoustic system enclosed in a pressure chamber permitted the sound pressure and the hydrostatic pressure to be varied independently over the range of 1–20 atm. The intensity of cavitation, as measured by the erosion rate of aluminum, was found to grow at an increasing rate with hydrostatic pressure. Experimental results obtained in this pressure range correlate with published Russian data taken at pressures up to 75 atm. A correspondence between cavitation erosion and electromagnetic radiation is postulated. The agreement between experimental results and those predicted by this correspondence is quite good.