NASA’s S-MODE mission was designed to measure and understand the complex oceanic features classified as “submesoscale,” i.e., features spanning up to 6.2 miles (10 kilometers) across. Such fine filaments and sharp density fronts in the ocean are responsible for fast and unpredictable changes in velocity, temperature, salinity, and even among small organisms called plankton in the surface layer of the ocean. A myriad of autonomous instruments, airborne sensors, and a fully equipped ship are part of the robust methods of measuring submesoscale dynamics in the California Current region.