Describe the relief of the Indian Ocean floor.

The Indian ocean is smaller than the Pacific and Atlantic. It is said to be the half ocean because it is blocked on the north by Asia. It does not reach to Arctic Sea in the north. In the south it extends up to the continent of Antarctica. Its average depth is 4000 metres which is lesser than that of these two oceans.

Trenches : The only famous trench is the Lunda Trench which lies south of the island of Java and runs parallel to it.

Ridges : There are a number of broad submarine ridges on the floor of Indian Ocean. A prominent ridge runs from Kanyakumari to Antarctica. It is situated in the middle and divides the ocean into two basins on either side. It is called the Lakshadweep-Chagos Ridge in the north, the St. Paul Ridge in the middle and the Amsterdam St. Plateau in the south, where it widens out considerably. There are two minor and parallel ridges which run north-westward. These are known as the Sacotra-Chagos Ridge and the Seychelles Ridges. The Madagascar Ridge and Prince Edward Crozet Ridges are other ridges. The Carlsberg Ridge divides Arabian sea into two parts. The Andaman and Nicobar Ridge extends from the mouth of the Irrawaddy to the Nicobar Islands.

Basins : The chief basins in the Indian Ocean are Central Basin, Arabian Basin, South Indian Basin, Mascarene Basin, West Australian and South Australian Basins.

Islands : The Andaman and Nicobar, Sri Lanka, Madagascar and Zanzibar islands are the parts of the continental blocks. The Lakshadweep Island is a coral island. The Mauritius and Reunion islands to the east of Madagascar are the volcanic origin.