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 goes a further 44 km to the Teraja Hills. From there, the border runs along the watershed between the Belait and Tutong rivers on one hand, and the Baram and Limbang rivers on the other hand. It then proceeds along the watershed of the Brunei and Limbang river basins, enters and runs along Sungai Mendaun, Sungai Melais and Sungai Menunggul (Menunggol) until its estuary at Brunei Bay. The land border between Malaysia and Brunei's Temburong District (which is separated from the other part of Brunei) starts at the estuary of the Pandaruan River and runs the entire length of the