Indonesia–Malaysia border Indonesia–Malaysia border The border between the Southeast Asian countries of Indonesia and Malaysia consist of both a land border separating the two countries' territories on the island of Borneo as well as maritime boundaries along the length of the Straits of Malacca, in the South China Sea and in the Celebes Sea. The land boundary has a length of 2,019.5 km and stretches from Tanjung Datu at the northwestern corner of Borneo, through the highlands of the Borneo hinterland, to the Gulf of Sebatik and the Celebes Sea in the eastern side of the island. The boundary separates the Indonesian
Brunei–Malaysia border at the 100 fathom isobath. In its 1979 territorial waters and continental shelf map, Malaysia claimed the area to be part of its continental shelf and depicted the Brunei-Malaysian border as running up to the 100 fathom isobath. Brunei did not recognise these assertions made by Malaysia. The Exchange of Letters signed on 16 March 2009 by the two countries provided for Malaysia's recognition of Brunei's territorial waters which it had earlier disputed. A joint committee is to determine the final maritime border between the two countries. See below for more on the dispute between the two countries. At its