Sebuku River

The Sebuku River is a river in Borneo that flows from Sabah, Malaysia to Nunukan, in the province of North Kalimantan, Indonesia.

Geography
The river flows in the northeastern area of Borneo island with predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification), and into the Celebes Sea.

The rivermouth is fronted by a small island called Pulau Senelak. A tidal bore occurs 3 days before and after spring tides, and its wave are high and rapid and can cause considerable damage to small craft.

History
The river was once taken as the southernmost border of the influence of Sultanate of Sulu on the island of Borneo in the 19th century, and hence is featured in the 1878 grant by Sultan of Sulu to British North Borneo Company.

At the end of the 19th century, this river again became a point of contention between the British North Borneo and Dutch Borneo, since the British regarded this river as its southernmost border with the Dutch, while the Dutch assumes a further northern boundary at Batu Tinagat, Tawau. The boundary dispute was settled in 1899 with a compromise solution of a border between these two extremities.