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
Brunei–Malaysia border portion of the South China Sea that is subject to multiple overlapping claims by China, Taiwan and Vietnam. Malaysia is also a claimant in the area but a bilateral agreement with Brunei has solved the overlapping claims over Brunei's territorial waters. From west to east, the Brunei–Malaysia border begins where the watershed of the Baram and Belait river basins meet the South China Sea at a point six nautical miles (11 km) east of Tanjung Baram with coordinates . It then travels along the watershed of the two river basins for about 30 km to the Pagalayan Canal. It then