One of the fundamental features of Indonesia is that it is an archipelagic state. Large-format maps of Indonesia usually show the straight baselines that join the outermost points of the outermost islands, thereby enclosing within a single entity the thousands of islands that make up the country and all the ‘archipelagic waters’ within the baselines (see Map 2.1). These maps also show the territorial sea that, except in a very few areas, extends 12 nautical miles out from these baselines and the exclusive economic zone (EEZ) that in most areas extends 200 nautical miles out from these same baselines. As a consequence much of the territory of Indonesia is made up of water. More precisely, water makes up about 58 per cent of the total area of 4.5 million square kilometres over which the state asserts its sovereignty, namely the land and water within the baselines and the territorial sea extending out from the baselines. The country's EEZ, within which the government exercises sovereign rights over all the living and non-living resources in the water and both on and under the seabed, gives the government limited jurisdiction over a further 5.4 million square kilometres. The result is a massive country Indonesia is the world's largest archipelagic state and has the third largest EEZ in the world.

Indonesia has, it must be noted, a number of disputes with its neighbours over the precise boundaries of some of its claims to maritime territory. In the most prominent of these, Indonesia and Malaysia both claim jurisdiction over a section of sea off the east coast of Kalimantan known as the Ambalat block; in 2005 tensions between them reached a peak when naval vessels from the two countries confronted one another in this area. Leaving aside disputes over what are, in relation to the whole, small patches of sea, however, the lines on a standard map of Indonesia are accepted by its neighbours. These lines, moreover, conform to the principles set out in the United Nations Convention on the Law of the Sea, ensuring that Indonesia's status as an archipelagic state has international recognition.