The Tropical Atlantic realm is one of twelve marine realms that cover the world's coastal seas and continental shelves. The Tropical Atlantic realm is one of twelve marine realms that cover the world's coastal seas and continental shelves. The Tropical Atlantic covers both sides of the Atlantic. In the western Atlantic, it extends from Bermuda, southern Florida, and the southern Gulf of Mexico through the Caribbean and along South America's Atlantic coast to Cape Frio in Brazil's Rio de Janeiro state. In the Eastern Atlantic, it extends along the African coast from Cape Blanco in Mauritania to the Tigres Peninsula on the coast of Angola. It also includes the seas around St. Helena and Ascension islands.