The Cayman Trough (also known as the Cayman Trench, Bartlett Deep and Bartlett Trough) is a complex transform fault zone pull-apart basin which contains a small spreading ridge, the Mid-Cayman Rise, on the floor of the western Caribbean Sea between Jamaica and the Cayman Islands. It is the deepest point in the Caribbean Sea and forms part of the tectonic boundary between the North American Plate and the Caribbean Plate. It extends from the Windward Passage, going south of the Sierra Maestra of Cuba toward Guatemala. The transform fault continues onshore as the Polochic-Motagua fault system, which consists of the Polochic and Motagua faults. This system continues on until the Chiapas massif where it is part of the diffuse triple junction of the North American, Caribbean and Cocos plates.
The relatively narrow trough trends east-northeast to west-southwest and has a maximum depth of 7,686 metres (25,217 ft). Within the trough is a slowly spreading north–south ridge which may be the result of an offset or gap of approximately 420 kilometres (260 mi) along the main fault trace. The Cayman spreading ridge shows a long-term opening rate of 11–12 mm/yr. The eastern section of the trough has been named the Gonâve Microplate. The Gonâve plate extends from the spreading ridge east to the island of Hispaniola. It is bounded on the north by the Oriente and Septentrional fault zones. On the south the Gonâve is bounded by the Walton fault zone, the Jamaica restraining bend and the Enriquillo-Plantain Garden fault zone. The two bounding strike slip fault zones are left lateral. The motion relative to the North American Plate is 11 mm/yr to the east and the motion relative to the Caribbean Plate is 8 mm/yr. The western section of the trough is bounded to its south by the Swan Islands Transform Fault.
