The Understanding Gulf Ocean Systems (UGOS) Initiative is part of the Gulf Research Program (GRP) focused on improving the skill of sustained continuous operational forecasts, and associated physical understanding, of ocean dynamics for the reduction of risks in offshore energy exploration and production in the Gulf of Mexico (GoM) where deep-water drilling and production occur and/or anticipated. This data catalog, sponsored by GRP/NASEM, compiles data sources used in the development and evaluation of hydrodynamic models for the Gulf of Mexico.