is a river and a large district of Sumatra. The district extends about 450 miles along the north-east coast. This district has a considerable trade, which is carried on by vessels from the coast of Coromandel, which supply cargoes of piece goods, and also raw silk, opium, and other articles, which they provide at Prince of Wales' island or Malacca, receiving in return gold, wax, sago, salted fish and fish roes, elephants' teeth, camphire, rattans, and other canes. Spars and masts, and large supplies of frame timber used to be imported by the Dutch East India Company for the use of Batavia. The maritime power of the kingdom of Siak has always been considerable.

The river Siak is one of the largest in the island, and discharges itself into the sea opposite Malacca in N. lat. 1.40. From a survey ordered by the British government of Prince of Wales' island, it appears that from its mouth to the town of Siak, is sixty-five miles. The width of the river is in general from about a half to three quarters of a mile, and its depth from seven to fifteen fathoms; but on the bar at low water, there is only fifteen feet of depth, and there are several shoals near its mouth.