The Caribbean Sea ( or /ˌkærɨˈbiːən/) is a tropical sea in the Western Hemisphere, part of the Atlantic Ocean, southeast of the Gulf of Mexico. A mediterranean sea, it covers most of the Caribbean Plate and is bounded on the south by South America, on the west and south by Mexico and Central America, and on the north and east by the Antilles: the Greater Antilles islands of Cuba, Hispaniola, Jamaica, and Puerto Rico lie to the north, and a plethora of Lesser Antilles bound the sea on the east. The entire area of the Caribbean Sea, the numerous islands of the West Indies, and adjacent coasts, are collectively known as the Caribbean.

The Caribbean Sea is one of the largest salt water seas and has an area of about 2,754,000 km² (1,063,000 square miles). The sea's deepest point is the Cayman Trough, between Cuba and Jamaica, at 7,686 m (25,220 ft) below sea level. The Caribbean coastline has many gulfs and bays: the Gulf of Venezuela, Gulf of Darien, Golfo de los Mosquitos and Gulf of Honduras.