Gulf of CaliforniaThe Gulf of California (Golfo de California), also known as the Sea of Cortés (Mar de Cortés) or Sea of Cortez, or less commonly as the Vermilion Sea (Mar Bermejo), is a marginal sea of the Pacific Ocean that separates the Baja California Peninsula from the Mexican mainland. It is bordered by the states of Baja California, Baja California Sur, Sonora, and Sinaloa with a coastline of approximately . Rivers that flow into the Gulf of California include the Colorado, Fuerte, Mayo, Sinaloa, Sonora, and the Yaqui.