The Southern Ocean exerts a strong influence on global biogeochemical cycles and air-sea gas fluxes. Significant progress has been made towards understanding the general patterns of circulation and biological productivity in this region, but the small-scale dynamics of surface water gases remain poorly resolved. Here we present new data documenting unprecedented spatial and temporal variability of Southern Ocean biogenic gases during the spring phytoplankton bloom. Using real-time underway mass spectrometry, we observed significant changes in surface water O2/Ar, pCO2, and dimethylsulfide (DMS) concentrations over time scales of days to weeks and sub-km spatial scales. Our results demonstrate a tight coupling between physical and biological processes controlling Southern Ocean gas distributions, and highlight the distinct biogeochemical dynamics governing gas cycling in open water and ice-covered regions.