This report introduces oceanographers to the International System of Units (SI) in physical oceanography. The SI constitutes a universal language, designed to be understood by all scientists. It facilitates their mutual comprehension and exchange of views and results of their work. The first part of the report is devoted to physical quantities, units and symbols, SI units and basic rules, and specific recommendations for the field of physical sciences of the ocean. The second part consists of tables of the quantities that are used in physical oceanography (fundamental quantities of seawater, physical properties of pure and seawater, dynamical oceanography, optical oceanography, marine geophysics, marine geochemistry, and chemical oceanography). Each table contains its preferred symbol, a short definition if necessary, and its unit in the SI, together with its symbol. Conversion factors between certain units and the corresponding (SI) units are given for dynamical oceanography and marine geophysics. (Author/JN)