Mid-oceanic ridge, which is the result of eruption of magma at the divergent plate boundary, is the significant feature of this ocean
The Atlantic is, generally speaking, S-shaped and narrow in relation to its length. The area of the Atlantic without its dependent seas is approximately 31,830,000 square miles (82,440,000 square km), and with them its area is about 41,100,000 square miles (106,460,000 square km). It has an average depth (with its seas) of 10,925 feet (3,300 metres) and a maximum depth of 27,493 feet (8,380 metres) in the Puerto Rico Trench, north of the island of Puerto Rico.
The ocean’s breadth from east to west varies considerably. Between Newfoundland and Ireland it is about 2,060 miles (3,320 km); farther south it widens to more than 3,000 miles (4,800 km) before narrowing again so that the distance from Cape São Roque, Brazil, to Cape Palmas, Liberia, is only some 1,770 miles (2,850 km). Southward it again becomes broader and is bordered by simple coasts almost without islands; between Cape Horn and the Cape of Good Hope the ocean approaches Antarctica on a broad front nearly 4,000 miles (6,500 km) wide.
Although not the largest of the world’s oceans, the Atlantic has by far the largest drainage area. The continents on both sides of the Atlantic tend to slope toward it, so that it receives the waters of a great proportion of the major rivers of the world; these include the St. Lawrence, the Mississippi, the Orinoco, the Amazon, the Río de la Plata, the Congo, the Niger, the Loire, the Rhine, the Elbe, and the great rivers draining into the Mediterranean, Black, and Baltic seas. In contrast to the South Atlantic, the North Atlantic is rich in islands, in the variety of its coastline, and in tributary seas. The latter include the Caribbean Sea, the Gulfs of Mexico and St. Lawrence, and Hudson and Baffin bays on the west and the Baltic, North, Mediterranean, and Black seas on the east.
This article treats the physical and human geography of the Atlantic Ocean as a whole. For detailed discussion of the physical and chemical oceanography and marine geology of the Atlantic Ocean, see ocean.