the Flevopolder, Flevoland which is kept at 3 metres below sea level. This body of water is then pumped up into the IJsselmeer.

It is sometimes called the Gelderse IJssel (; "Gueldern IJssel") to distinguish it from the Hollandse IJssel. It is in the provinces of Gelderland and Overijssel, the latter of which was named after this river. The Romans