An equation for sound absorption in Lyman and Fleming sea water (S= 35‰, pH=8) is presented as a function of frequency. temperature, and pressure. It represents the contributions to absorption due to boric acid, magnesium sulfate, and water. The pressure effect on sound absorption by magnesium sulfate is treated in more detail than Schulkia and March did. The equation is based on the laboratory work at atmospheric pressure by Simmons for MgSo4 and boric acid, on the pressure work by Fisher in 0.5m MgSO4 solutions, and on pressure work by Litovitz and Carnevale in pure water. For frequencies from 10 to 400 kHz up to pressures of 500 atm the absorption is substantially lower than that calculated from the Schulkin and Marsh equation. The pressure results are in good agreement with field data obtained by Bezdek. [Work supported by Office of Naval Research.]