Yesterday was the 81st birthday of Walter Munk, a geophysicist whose work has led to a better understanding of ocean currents, circulation, and tides. During World War II, Munk and Harald Sverdrup, then director of the Scripps Institution of Oceanography in La Jolla, California, developed a method to predict surf conditions on beaches--an important tool for military amphibious landings. As a member of the American Miscellaneous Society, Munk helped initiate the Moho project to drill into oceanic crust. This research evolved into the Deep Sea Drilling Project, which has sampled sea-floor sediment around the globe. Most recently, Munk--a longtime researcher at Scripps--headed the Acoustic Thermometry of Ocean Climate Project that aims to measure ocean temperature with sound pulses.