The Temperate Northern Atlantic is a biogeographic region of the Earth's seas, comprising the temperate and subtropical waters of the North Atlantic Ocean and connecting seas, including the Mediterranean Sea, Black Sea, and northern Gulf of Mexico.
The Temperate Northern Atlantic is a marine realm, one of the great biogeographic divisions of the world's ocean basins.
The tropical waters of the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea are part of the Tropical Atlantic marine realm. To the north, the Temperate North Atlantic transitions to the Arctic realm.
The Temperate Northern Atlantic realm is divided into six marine provinces. Five of the provinces are further divided into marine ecoregions. The Black Sea is both a province and an ecoregion.