Brunei–Malaysia border which are defined by agreements, from west to east, are as follows: Brunei and Malaysia in an Exchange of Letters on 16 March 2009, agreed to affirm the five agreements. The two countries also agreed to use the watershed principle to determine the remaining undelimited portions of the border. Brunei's maritime boundary with Malaysia until the 100 fathom isobath was inherited from the Sarawak (Definition of Boundaries) Order in Council 1958 No 1518 and the North Borneo (Definition of Boundaries) Order in Council 1958 No 1517, both of which defined the boundary between Brunei on the one hand, and Sarawak
Indonesia–Malaysia border Island. A stretch of the Indonesia–Malaysia border will run in between. This will effectively establish three Indonesia-Malaysia-Singapore tripoints in the area. The determination of boundaries to fill the various gaps and defining the various tripoints would require Indonesia-Malaysia-Singapore trilateral negotiations. Again, the only a continental shelf boundary has been agreed to in this segment of the maritime border between the two countries. The boundary begins at Point 21 with coordinates 109° 38'.8E 02° 05'.0N (109° 38' 48"E 02° 05'N) off Tanjung Datu at the western extremity of the Malaysia state of Sarawak. Incidentally, the Indonesian baseline at Tanjung Datu is