Borneo - Geography

Geography

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. 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.

With an area of 743,330 square kilometres (287,000 sq mi), it is the third-largest island in the world. Its highest point is Mount Kinabalu in Sabah, Malaysia, with an elevation of 4,095 m (13,435 ft).

The largest river system is the Kapuas in West Kalimantan with a length of 1,143 km (710 mi). Other major rivers include the Mahakam in East Kalimantan (980 km long (610 mi), the Barito in South Kalimantan (880 km long (550 mi)), and Rajang in Sarawak (562.5 km (349.5 mi))).

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 (330 ft) deep.

Before sea levels rose at the end of the last Ice Age, Borneo was part of the mainland of Asia, forming, with Java and Sumatra, the upland regions of a peninsula that extended east from present day Indochina and Thailand. The South China Sea and Gulf of Thailand now submerge the former low-lying areas of the peninsula. Deeper waters separating Borneo from neighboring Sulawesi prevented a land connection to that island, creating the divide between Asian and Australia-New Guinea biological regions known as Wallace's Line.