A surface mooring named the East Sea Real-time Ocean Buoy (ESROB) has been operated since 1999 off the mid-east coast of Korea. The ESROB is located 9 km off the coast (37° 32.24’N; 129° 12.92’E) in a water depth of 130 m providing meteorological and oceanographic (physical and biogeochemical) data every 10 minutes from sensors such as Conductivity-Temperature-Depth (CTD) and acoustic Doppler current profiler (ADCP) instruments. The data provided here are quality controlled and quality assured via typical data processing methods. The data have been used to address seasonal and interannual variations in currents, wind-and tide-induced internal waves, and physical and biological water properties (see related publications noted on this web page). The uploaded data files contain variables in NetCDF format that are obtained during each deployment.