Diemel
Source1 locationSauerland
Source1 coordinates51°15′59″N 8°39′05″E
Mouth locationWeser
Mouth coordinates51°38′33″N 9°26′52″E
CountryGermany
Length110.4 km (68.6 mi)
Source1 elevation680 m (2,230 ft)
Tributaries rightTwiste

The Diemel (ˈdiːml̩) is a river in Hesse and North Rhine-Westphalia, Germany. It is a western and orographically left tributary of the Weser. It is the first, and therefore southernmost, of the larger Weser tributaries after its formation at the confluence of the Fulda and Werra rivers.

The Twiste is a tributary of the Diemel, joining the latter from the right in Warburg.

Route

The source of the Diemel is near Willingen, in Sauerland. The Diemel flows generally northeast through the towns Marsberg, Warburg, and Trendelburg. It flows into the Weser in Bad Karlshafen.