The Gulf of California Marine Program undertakes annual surveys of the different habitats across the Gulf. Established in 1998, our underwater monitoring effort includes population counts, species biodiversity data, and description of ecosystem roles. We focus on four main factors concerning fish and invertebrates: diversity, density, biomass, and size. This data is collected at different sites with similar characteristics, as well as at the same sites over time to make effective comparisons at local and regional scales. Producing robust, objective scientific information that builds a comprehensive understanding of connections between marine ecosystems and humans.