The Zaan is a small river in the province of North Holland in the northwestern Netherlands and the name of a district through which it runs. The river was originally a side arm of the IJ bay and travels 10 kilometers through the municipalities of Zaanstad ("Zaan City") and Wormerland north of Amsterdam, from West-Knollendam in the north to Zaandam in the south, where it empties into the IJ.