The name contains the digraph ij, used throughout modern Dutch orthography, which is why both letters appear capitalized (as in: IJmuiden and IJsselmeer).

The name IJssel (older Isla, Isala, from *Īsalō), is thought to either have been derived from a Proto-Indo-European root *eis- "to move quickly" (Old Norse eisa "to race forward", Latin ira "anger")[1] or a possible Old European stratum source.

[2] Before the Roman Warm Period, the Zuiderzee in highly glaciated times was a brackish, sometimes tidal, very broad set of mudflats, the Vlies (Latin: Flevo).

The IJssel and Amstel kept a saline-freshwater balance, and northward flow, enabling islands and banks to build up.

Among these are rare zones just above sea level: Kampen, Elburg and north-east bank once wooded strip from Nijemirdum to Stavoren.

However, the North Sea, locally to form (or re-form) the Zuiderzee, reasserted itself – the so-called Dunkirk transgressions.

The submerged old delta is traceable out from its sea level elevation point at Zwolle throughout the broadest parts of the IJsselmeer; the lands of Emmeloord, Lelystad and south of Dronten are relatively recent reclamations.

It seems that the firmly below-sea-level excoriations in the far north (the Groote Vliet) by Medemblik and the IJ (near Amsterdam) were all deep parts of the same body of water in the height of the Roman Warm Period and Medieval Dark Age sea rises (transgressions).

The river was a natural barrier and in April 1945 was stormed by assault troops of the Allied armies liberating the Netherlands from the occupying forces of Nazi Germany.

The IJssel, if accepted as a branch of the Rhine-Meuse-Scheldt delta, is the only one that takes up tributary rivers rather than giving rise to distributaries.

The following canals, long ditches and tributary streams feed the IJssel, in downstream order: Road bridges across river IJssel (with nearest places on the left and right bank): Railroad bridges (with nearest train station on the left and right bank): Only those ferries capable of carrying motorised vehicles are included.