Presents the online version of "Our Restless Tides," which explains the basic astronomical factors producing tides and tidal currents. Offers information on astronomical tide-producing forces, differential tide-producing forces, tidal inequalities, and factors influencing tide arrival times. Provides information on tide prediction. Links to the the home page of the National Oceanic and Atmospheric Administration (NOAA) Oceanographic Products and Services Division (OPSD) and to a list of its publications.