This chapter presents an overview on climatic and hydrographic factors that are particularly relevant for the understanding of spatial and temporal patterns in marine biodiversity. It describes some climatic processes or parameters that are of primary importance to explain ecogeographical patterns in diversity. The chapter provides a primer in applied climatology and physical oceanography to understand more deeply the potential links between hydro-climatic processes and marine biodiversity. It explains oceanic circulation, which is the result of the unequal distribution of the energy at the earth's surface due to the inclination of our planet. The chapter explores some important mechanisms involved in the oceanic circulation, and explains large-scale ecogeographical patterns in biodiversity. The surface oceanic circulation plays a prominent role in the redistribution of heat throughout the planet. A deep examination of the relationships between oceanic and atmospheric circulation indicates that there are some differences.