Arut River is a river in the province of Kalimantan Tengah, island of Borneo, Indonesia, about 700 km northeast of the capital Jakarta. It is a tributary of the Lamandau River. The river flows through the north side of Pangkalan Bun town.
The river flows in the southern area of Kalimantan with a predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification). The annual average temperature in the area is 24 ðC. The warmest month is October, when the average temperature is around 24 ðC, and the coldest is July, at 22 ðC. The average annual rainfall is 2778 mm. The wettest month is November, with an average of 570 mm of rainfall, and the driest is September, with 66 mm of rainfall.