Sea level measurements have proven to be extremely valuable for investigations of the dynamics of the world's oceans. Although a comprehensive review of studies using sea level is beyond the scope of this article, it can give an idea of the impact that these data have had on the development of our understanding of ocean and ocean‐atmosphere dynamics. The discussion is restricted geographically and temporally to the variability of the Pacific Ocean on time scales longer than several days and is organized into two broad categories. The main section is concerned with the description of a few selected phenomena that are conveniently divided according to their time scale. For example, research studies concerned with the dynamics of the seasonal cycle of the Pacific Ocean are covered. This category also contains a description of the important work on interannual sea level fluctuations and their relationship to global climate disturbances, followed by a short discussion of the use of sea level variability as a tool for monitoring other interesting quantities that are difficult to observe directly. For example, the use of the geostrophic approximation allows sea level differences to be interpreted as an index for surface currents. The article concludes with a brief discussion of several developing technologies that promise further advances in our understanding of Pacific sea level variability.