The Caribbean Sea is a vast body of water located in the western Atlantic Ocean, bordered by the Greater Antilles to the north, the Lesser Antilles to the east, and the coasts of Central and South America to the south and west. This marginal sea is one of the largest in the world, serving as a major conduit for oceanic currents flowing toward the Gulf of Mexico. Its underwater landscape reveals a complex bathymetry, ranging from shallow coastal shelves to some of the planet’s deepest trenches.
Understanding Average Depth
The overall measure of the Caribbean Sea’s depth places it firmly among the world’s deeper marginal seas, with an average depth of approximately 2,200 meters (7,220 feet). This high average is a direct result of its unique structure, which is not a single, uniform basin. The seafloor is divided into several distinct, deep depressions, including the Yucatán, Colombian, Venezuelan, and Grenada Basins. These large basins are separated by submarine ridges and rises, preventing the sea from being dominated by shallow continental shelf areas.
The Deepest Point
The maximum depth of the Caribbean Sea is found within the Cayman Trough, a narrow, submerged valley located between the island of Jamaica and the Cayman Islands. This trench, sometimes referred to as the Bartlett Deep, holds the lowest point in the entire sea. The maximum recorded depth here plunges to 7,686 meters (25,217 feet) below the sea surface. The Cayman Trough stretches for hundreds of kilometers, forming a significant geological feature in the western part of the sea.
Geological Forces Shaping the Sea Floor
The dramatic depth and steep slopes of the Caribbean seafloor are a consequence of intense plate tectonic activity over millions of years. The region is a dynamic boundary where the Caribbean Plate interacts with the surrounding North American and South American Plates.
The Lesser Antilles arc along the eastern boundary was formed by the ongoing subduction of the Atlantic crust beneath the Caribbean Plate. This process of one plate sliding beneath another creates the deep trenches and volcanic island chains characteristic of the eastern Caribbean.
The formation of the deepest point, the Cayman Trough, is due to a complex transform fault zone. This tectonic line marks the boundary where the North American Plate scrapes horizontally past the Caribbean Plate. The sideways, or left-lateral strike-slip, motion along faults creates a “pull-apart basin” where the Earth’s crust is stretched and thinned. This stretching allows the seafloor to drop drastically, forming the ultra-deep trough.
The Cayman Trough even includes a small, active spreading center, the Mid-Cayman Rise, where new oceanic crust is slowly being formed. This ultraslow spreading occurs at a rate of only about 11 to 12 millimeters per year. The combination of strike-slip faulting and localized spreading explains the extreme depth and narrow, elongated shape of the trough.
How Caribbean Depth Compares Globally
The Caribbean Sea’s average depth of 2,200 meters places it in a distinct category when compared to the world’s major water bodies. It is considerably deeper than other large marginal basins like the Mediterranean Sea, which has an average depth of approximately 1,500 meters (4,900 feet).
However, its depth is significantly less than that of the world’s true oceans. The average depth of the entire Atlantic Ocean is about 3,646 meters (11,962 feet), and the Pacific Ocean is even deeper, averaging around 4,000 meters (13,000 feet). The Caribbean Sea’s floor, while deep, does not reach the average abyssal plains of the main oceanic basins.