The South and Little Andaman are separated by

Duncan Passage is a strait in the Indian Ocean. It is about 48 km (30 mi) wide; it separates Rutland Island (part of Great Andaman) to the north, and Little Andaman to the south. West of Duncan Passage is the Bay of Bengal; east is the Andaman Sea.

Several small islands and islets lie along the passage. North to south, they are:

North Cinque Island
South Cinque Island
Passage Island
The Sisters
North Brother Island
South Brother Island

Manners Strait is the branch of Duncan Passage that lies between North Cinque Island and Rutland Island.