The Central Indian Ridge (CIR) is a divergent tectonic plate boundary between the African Plate

African Plate

The African Plate is a tectonic plate which includes the continent of Africa, as well as oceanic crust which lies between the continent and various surrounding ocean ridges.-Boundaries:...

 and the Indo-Australian Plate

Indo-Australian Plate

The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters...

, traversing the western regions of the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

. The northern section of the CIR is also called the Carlsberg Ridge

Carlsberg Ridge

The Carlsberg Ridge is the northern section of the Central Indian Ridge, a divergent tectonic plate boundary between the African Plate and the Indo-Australian Plate, traversing the western regions of the Indian Ocean....

.

The CIR extends northward from a triple point

Triple point

In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases of that substance coexist in thermodynamic equilibrium...

 junction near the island of Rodrigues

Rodrigues (island)

Rodrigues , sometimes spelled Rodriguez but named after the Portuguese explorer Diogo Rodrigues, is the smallest of the Mascarene Islands and a dependency of Mauritius...

 (the Rodrigues Triple Point

Rodrigues Triple Point

The Rodrigues Triple Point is a geologic triple junction in the southern Indian Ocean where three tectonic plates meet: the African Plate, the Indo-Australian Plate, and the Antarctic Plate...

) to a junction with the Owen Fracture Zone

Owen Fracture Zone

The Owen Fracture Zone is a transform fault which runs along the eastern boundary of the Arabian Plate, separating it from the Indo-Australian Plate for most of its length, and from the African Plate for a much shorter distance...

. The islands of Saint-Paul

Île Saint-Paul

Île Saint-Paul is an island forming part of the French Southern and Antarctic Lands in the Indian Ocean, with an area of . It is located about southwest of the larger Île Amsterdam, and south of Réunion...

 and Amsterdam

Île Amsterdam

New Amsterdam, Amsterdam Island, or Île Amsterdam is a French island in the Indian Ocean located at . It is part of the French Southern and Antarctic Lands.- History :...

are the above-water parts of the Central Indian Ridge.