An initial segment for the maritime boundary between Indonesia and Thailand was defined by a bilateral agreement that was reached in 1971. It followed an equidistance line for 89 nautical miles in the Andaman Sea and Malacca Strait. In 1975, Indonesia and Thailand agreed to extend the boundary northwards into the Andaman Sea for an additional 75 nautical miles. This section of the boundary was not based on equidistance, with the Parties instead opting to follow the geomorphologic divide of the continental shelves, which slightly favored Thailand.

Both the northern tripoint with India (point T), and the southern tripoint with Malaysia (common point), have been established. An agreement between Indonesia, Malaysia, and Thailand was signed on 21 December 1971 (only four days after the 1971 Indonesia–Thailand maritime boundary Agreement) on their common junction point in the Malacca Strait. On 22 June 1978, India, Indonesia, and Thailand reached a similar agreement on the location of their tripoint in the Andaman Sea.

Map showing the maritime boundary between Indonesia and Thailand

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