Rupel is a tidal river in northern Belgium. It is about 12 km long. It flows through the Belgian province Antwerp. It is formed by the confluence of the rivers Dijle and Nete, in Rumst. It flows into the Scheldt at Rupelmonde. Towns along the Rupel are Boom and Niel. The Rupel is navigable, and forms part of the waterway to Brussels.