The Indragiri River is a river in Sumatra, in the Indonesian province of Riau, about 800 km northwest of the capital Jakarta.

[2][3] Formed by the union of the Ombilin River and the Sinamar River, the Indragiri empties into the Strait of Malacca.

[4] The river flows in the eastern area of Sumatra with predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification).

The warmest month is February, when the average temperature is around 24 °C, and the coldest is August, at 22 °C.

The wettest month is November, with an average of 345 mm rainfall, and the driest is January, with 107 mm rainfall.