The Sunda Strait is located between the Indonesian islands of Java and Sumatra and connects the Java Sea to the Indian Ocean. There are a number of small islands that are mainly volcanic in origin located in the Strait including Sangiang, Sebesi, Sebuku, Panaitan and most famously, the Krakatau Islands: Lang, Verlaten, Krakatau, and Anak Krakatoa.

The eruption of Krakatau in 1883 devastated the islands of the Strait and the nearby surrounding regions of Java and Sumatra and many areas have never been resettle, including the coastal region of Java that is now incorporated into the Ujung Kulon National Park, but now much of the coastline is actually very densely populated.

The Strait is oriented in a roughly north-east/south-west direction and has a minimum width of 24 kilometres at its north-eastern end between Cape Tua on Sumatra and Cape Pujat on Java. At its western end it is very deep but it becomes much shallower as it narrows to the east, with a depth of only 20 metres in some areas of the eastern end making it notoriously difficult to navigate, with very strong tidal flows, sandbanks, and man-made obstructions like the oil platforms off the Java coast. These constraints make it unsuitable for large modern ships which use the Strait of Malacca instead, however historically it was an important shipping route for centuries for the Dutch East India Company travelling to the Spice Islands of Indonesia.