Borneo (Malay: Borneo, Indonesian: Kalimantan) is the third largest island in the world and is located north of Australia, at the geographic centre of Maritime Southeast Asia.

The island is divided among three countries: Brunei, Indonesia and Malaysia. Approximately 73% of the island is Indonesian territory (Kalimantan). The Malaysian states of Sarawak and Sabah (East Malaysia), in the north, occupy about 26% of the island. The sovereign state of Brunei, located on the north coast, comprises about 1% of Borneo’s land area.

Borneo is surrounded by the South China Sea to the north and northwest, the Sulu Sea to the northeast, the Celebes Sea and the Makassar Strait to the east, and the Java Sea and Karimata Strait to the south. It is the largest island in the Malay archipelago, to the west of Borneo are the Malay Peninsula and Sumatra, to the south is Java, to the east is Sulawesi and to the northeast, the Philippines.

Borneo’s highest point is Mount Kinabalu in Sabah, Malaysia, with an elevation of 4,095 m above sea level it is the third highest peak in South East Asia, making Borneo the world’s third highest island.

The largest river system is the Kapuas in West Kalimantan. With a length of 1,143 km, it is the longest river in Indonesia. Malaysia’s longest river, the Rajang, lies in Sarawak and is 562.5 km long. Other major rivers include the Barito in South Kalimantan 880 km long  and the Mahakam in East Kalimantan 980 km long .

Borneo has significant cave systems. Clearwater Cave, for example, has one of the world’s longest underground rivers. Deer Cave is home to over three million bats, with guano accumulated to over 100 metres .

The following is a list of top 20 urban areas in Borneo.