Sulawesi Sea Boundaries Still Unsettled After Decades of Talks

The article below by I Made Andi Arsana. Lecturer in Geodetic Engineering at Gadjah Mada University, Researcher on the Geospatial Aspects of the Law of the Sea, and United Nations Conciliator representing Indonesia in Maritime and Law of the Sea Affairs)

Here’s his analysis:

Ambalat, Once Again
By I Made Andi Arsana
August 12, 2025

Two decades have passed, and the Ambalat issue has resurfaced. One of the sparks this time is the agreement between President Prabowo Subianto of Indonesia and Prime Minister Anwar Ibrahim of Malaysia to explore avenues for cooperation in the Ambalat waters.

It is important to understand that Indonesia and Malaysia have yet to agree on the maritime boundary in this area. Both countries are still in the process of defining an official and precise border.

Many assume that “Ambalat” refers to the entire stretch of sea east of Borneo (Kalimantan). This is inaccurate. Ambalat is not the official name of the sea. Internationally, the area is recognized as the Sulawesi Sea, as recorded in the official S-23 document issued by the International Hydrographic Organization (IHO).

Indonesia has claimed parts of the Sulawesi Sea since the 1960s by dividing it into oil and gas concession blocks. Specifically, in 1999 Indonesia created the Ambalat Block, and in 2004, the East Ambalat Block. These were designated for exploration and exploitation by international companies under Indonesian concession.

In reality, Ambalat represents only a small portion of Indonesia’s overall claim in the region. The official name of the sea remains the Sulawesi Sea.