The Global Ocean Forecast System (GOFS 3.1) is an operational global ocean/ice nowcasting and forecasting system that runs daily at the Naval Oceanographic Office. GOFS is based on the HYbrid Coordinate Ocean Model (HYCOM), two-way coupled to the Community Ice CodE (CICE) and using the Navy Coupled Ocean Data Assimilation (NCODA). It runs daily at the Navy DoD Supercomputing Resource Center, creating a nowcast through a 7-day forecast. The system 1) depicts the location of mesoscale features such as oceanic eddies and fronts and provides 2) accurate 3-dimensional ocean temperature, salinity, and current structure, 3) boundary conditions for regional and nested coastal models, 4) acoustical proxy measures (mixed layer depth, sonic layer depth, below layer gradient and deep sound channel axis), and 5) ice concentration, thickness and drift.