Cayman Trough in the context of "Motagua Fault"

The Caribbean Sea is a sea of the North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba to Puerto Rico, the Lesser Antilles to the east from the Virgin Islands to Trinidad and Tobago, South America to the south from the Venezuelan coastline to the Colombian coastline, and Central America and the Yucatán Peninsula to the west from Panama to Mexico. The geopolitical region around the Caribbean Sea, including the numerous islands of the West Indies and adjacent coastal areas in the mainland of the Americas, is known as the Caribbean.

The Caribbean Sea is one of the largest seas on Earth and has an area of about 2,754,000 km (1,063,000 sq mi). The sea's deepest point is the Cayman Trough, between the Cayman Islands and Jamaica, at 7,686 m (25,217 ft) below sea level. The Caribbean coastline has many gulfs and bays: the Gulf of Gonâve, the Gulf of Venezuela, the Gulf of Darién, Golfo de los Mosquitos, the Gulf of Paria and the Gulf of Honduras.

The Puerto Rico Trench is located on the boundary between the North Atlantic Ocean and Caribbean Sea, parallel to and north of Puerto Rico, where the oceanic trench reaches the deepest points in the Atlantic Ocean. The trench is associated with a complex transition from the Lesser Antilles frontal subduction zone between the South American plate and Caribbean plate to the oblique subduction zone and the strike-slip transform fault zone between the North American plate and Caribbean plate, which extends from the Puerto Rico Trench at the Puerto Rico–Virgin Islands microplate through the Cayman Trough at the Gonâve microplate to the Middle America Trench at the Cocos plate.

Constituting the deepest points in the Atlantic Ocean, the trench is 810 kilometres (503 mi) long and has a maximum documented depth between 8,376 metres (27,480 ft) and 8,740 metres (28,675 ft). The deepest point is commonly referred to as the Milwaukee Deep, with the Brownson Deep naming the seabed surrounding it. However, more recently, the latter term has also been used interchangeably with the former to refer to this point. The exact point was identified by the DSSV Pressure Drop using a state-of-the-art Kongsberg EM124 multibeam sonar in 2018, and then directly visited and its depth verified by the crewed submersible Deep-Submergence Vehicle DSV Limiting Factor (a Triton 36000/2 model submersible) piloted by Victor Vescovo.

The Mid-Cayman Rise or Mid-Cayman Spreading Center is a relatively short (110 km long) divergent plate boundary in the middle of the Cayman Trough. It forms part of a dominantly transform boundary that is part of the southern margin to the North American Plate. It is an ultra-slow spreading center where the North American Plate is rifting away from the Caribbean Plate with an opening rate of 15–17 mm per year.

The Walton fault zone is a major active left lateral (sinistral) strike-slip fault, forming part of the southern boundary to the Cayman Trough. It extends from the Mid-Cayman Rise spreading center in the west to Jamaica in the east. It has a total length of about 360 km and is formed of several sub-parallel strands. Together with the Enriquillo-Plantain Garden fault zone it forms the southern boundary of the Gonâve Microplate. It is associated with only moderate earthquakes with magnitudes of less than 6.

The Swan Islands Transform Fault is an active left-lateral (sinistral) strike-slip fault zone that forms part of the boundary between the Caribbean plate and the North American plate. It runs along the southern boundary of the Cayman Trough from the Mid-Cayman Rise spreading center in the east, to Guatemala in the west, where it continues as the Motagua Fault. It consists of two main fault strands that overlap west of the Swan Islands. It has been associated with several major earthquakes, including those in 2009, 2018 and 2025.

In geology, a trough is a linear structural depression that extends laterally over a distance. Although it is less steep than a trench, a trough can be a narrow basin or a geologic rift. These features often form at the rim of tectonic plates. There are various oceanic troughs on the ocean floors.Troughs created by glaciation are called glacial trough.