Sulawesi Sea Boundaries Still Unsettled After Decades of Talks

Overlapping Claims.

The Sulawesi Sea is not under Indonesia’s sole jurisdiction; Malaysia also has sovereign rights there. Malaysia’s official claim was laid out in its 1979 New Map, which overlaps with Indonesia’s earlier claims. This map was protested not only by Indonesia but also by the Philippines. Nevertheless, both Indonesia and Malaysia have made unilateral claims in the Sulawesi Sea.

The Ambalat (1999) and East Ambalat (2004) blocks significantly overlap with Malaysia’s 1979 claim. In 2005, Malaysia issued its own oil and gas concession blocks, ND6 and ND7. Although they lie within Malaysia’s 1979 claim line, these blocks also overlap substantially with Indonesia’s Ambalat concessions—leading to what became known as the 2005 Ambalat dispute.

The competition arises because both countries are entitled to maritime zones in the area under the United Nations Convention on the Law of the Sea (UNCLOS) 1982. Coastal states have rights to maritime zones measured from their baselines.

Delimitation Process.
Maritime zones include the territorial sea (12 nautical miles), contiguous zone (24 nautical miles), exclusive economic zone (EEZ, 200 nautical miles), and the continental shelf, which can extend beyond 200 nautical miles.

For neighboring states like Indonesia and Malaysia, these zones naturally overlap. This makes delimitation—the process of drawing maritime boundaries—essential. Such delimitation requires geospatial and geodetic expertise to determine exact coordinates.

The process usually begins with bilateral negotiations. If talks fail, the matter may be taken to the International Court of Justice (ICJ) or the International Tribunal for the Law of the Sea (ITLOS). Before delimitation, each country typically presents its own proposed boundary.