Diemelsee
Municipality
Coat of arms
Location of Diemelsee within Waldeck-Frankenberg district
Location of Diemelsee
Diemelsee Show map of Germany Diemelsee Show map of Hesse
Coordinates: 51°22′N 08°48′E / 51.367°N 8.800°E / 51.367; 8.800
Country	Germany
State	Hesse
Admin. region	Kassel
District	Waldeck-Frankenberg
Subdivisions	13 Ortsteile
Government
• Mayor (2023–29)	Volker Becker[1]
Area
• Total	121.59 km2 (46.95 sq mi)
Elevation	388 m (1,273 ft)
Population  (2023-12-31)[2]
• Total	4,686
• Density	38.54/km2 (99.82/sq mi)
Time zone	UTC+01:00 (CET)
• Summer (DST)	UTC+02:00 (CEST)
Postal codes	34519
Dialling codes	05633
Vehicle registration	KB
Website	gemeinde-diemelsee.de

Diemelsee (German pronunciation: [ˈdiːml̩ˌzeː]) is a municipality in Waldeck-Frankenberg in northwest Hesse, Germany, and is part of the low mountain region called Upland. Adorf is the seat of this municipality.

Diemelsee lies on the river Diemel in the Diemelsee Nature Park just upstream from and southwest of the Diemelsee reservoir. The town of Korbach is found about 10 km to the southeast, and the town of Paderborn 39 km to the north.

Diemelsee borders in the north on the town of Marsberg (Hochsauerlandkreis in North Rhine-Westphalia), in the northeast on the town of Bad Arolsen, in the east on the municipality of Twistetal, in the south on the town of Korbach, in the southwest on the municipality of Willingen (all in Waldeck-Frankenberg), and in the west on the town of Brilon (Hochsauerlandkreis).

The municipality of Diemelsee came into being as part of municipal reform in 1971 through the voluntary merger of the following 13 centres:

The municipality's administrative seat is in Adorf, which with a population of 1750 is also the biggest of the 13 centres.

Note: FWG is a citizens' coalition.

The council's 31 seats are apportioned in accordance with municipal elections last held on 26 March 2006. Results for the 1997 and 2001 elections are also shown.

Diemelsee's civic coat of arms might heraldically be described thus: Party per bend wavy, above, in Or an eight-pointed star sable, below, in azure a five-petalled rose argent with centre Or and sepals vert.

The black eight-pointed star is the star of Waldeck.

Well known outing destinations near Diemelsee are the Diemelsee reservoir and the Upland (a German name, pronounced [ˈuː.plant], not as the English word). In Adorf is a visitors' mine, the Grube Christiane.

The inhabitants earn their livelihood mainly through agriculture, trades, small industry or the tourist trade.

• Gemeinde Diemelsee