Interpretation of attenuation measurements in the Baltic Sea [H. G. Schneider, R. Thiele, and P. C. Wille, J. Acoust. Soc. Am. (to be published, 1985)] indicates a need for estimating sound absorption in low salinity waters. While the magnesium sulfate component depends simply on the first power of salinity, the low‐frequency boric acid relaxation is more complex. The mechanism involves exchange with carbonate in which the ion‐pair calcium carbonate affects only the absorption magnitude αmax. Absorption measurements by the resonator method (at elevated boric acid concentrations) show roughly 0.5 power dependence on calcium concentration in the range of interest. The Baltic salinity is roughly14normal while the carbonate and acidity (pH≃8.0) are both normal. Since αmaxdepends on the concentration product,S1.5dependence gives a reduction by the factor 8 which makes it negligible. The relaxation frequencyfrdepends on a sum of concentrations and is estimated to be reduced by the factor 1.6. Laboratory measurements offrin Baltic water samples by the temperature‐jump method show reasonable agreement. We conclude that the boric acid relaxation probably plays no role in Baltic Sea attenuation.