At the entrance to the lake it makes sense to stop near the tourist information center (N 51 10.116 E 9 04.574). There is a cafe, a small lake and an unusual house.
A little further along the road there is a tourist zone in the style of the Wild West (N 51 10.103 E 9 03.210) and an excellent view of the village of Hemfurth.
Then we parked near the dam (N 51 11.019 E 9 03.724) and climbed to the Uhrenkopfkanzel viewpoint. Find the path on this map https://www.openstreetmap.org/#map=18/51.18438/9.06266, it is called there Auf den Klippen.
We went downstairs and crossed the dam to the village of Edersee, where we had lunch. The dam was built in 1908-1914. During the Second World War, it was bombed and partially destroyed. The hole created a wave, 6-8 meters high, which swept along the river bed for 30 kilometers. Reconstruction of this attack can be seen in the movie The Dam Busters (1955) (video).
In connection with the flood, foreign mass media reported the death of 749 prisoners of one of the concentration camps, but Germany did not confirm this information.
The dam was restored quickly, in a few months.
Illumination of the Eder dam.
Next we went up to the Waldeck Castle. Now it is a 4-star hotel and museum, you can freely enter the territory. The observation deck offers a great view of the lake, though not in the afternoon when the sun shines directly in the eye.
The first mention of the castle dates back to 1120, and the first owner was Volkwin II von Schwalenberg. He received the title Count Waldeck and for 500 years his heirs owned the castle until they moved to Bad Arolsen.
The castle was built on top of a cliff, it is clearly visible in front of the gate.
After the original owners moved, inside were military huts, a national archive, and even a women's prison.
The hotel opened in 1906 and until 2009 was state owned.
Getting there: small, free parking near the dam N 51 11.019 E 9 03.724, paid parking near the castle N 51 12.232 E 9 03.469. Buses are only seasonal, here (https://www.nvv.de/freizeit-events/ausflugsziele/edersee-saisonverkehr/) you can see the PDF flyer with the names of the stops and a route planner.