Recent measurements by Del Grosso show a discrepancy between computed and observed values of sound velocity in sea water. The basis of Kuwahara's formula has been re-examined. The chief cause of the discrepancy lies in the use of a value for the compressibility of pure water that is too large.
Beyer, Robert T.. 1954. "Formulas for sound velocity in sea water." Journal of Marine Research 13, (1). https://elischolar.library.yale.edu/journal_of_marine_research/807