Overview
A signposted loop of 9.0 km on the north-west side of the Hennesee, the reservoir held back by the Hennetalsperre above Meschede. It is waymarked as A3 — a black rectangle with the code in it — and maintained by the Sauerländischer Gebirgsverein, so the signs, not the name, are what to follow on the ground.
The walk begins at the Badebucht car park by the shore and runs east, close to the water and nearly level, to the lowest ground on the route at about 315 m near the dam end of the lake. A memorial stands beside the path on this stretch. The loop then turns away from the water and climbs, steadily rather than steeply and mostly on forest roads, over the flank of the Lannenberg and along the eastern side of the Schatenberg to about 460 m — roughly 150 m above the water, with 261 m of ascent counted over the whole circuit. The descent runs back down the western side and reaches the lake again at the Berghausener Bucht, a few hundred metres short of the car park it started from. A steel sculpture called Im Dreieck stands 262 m off the line at the eastern turn, with no mapped way joining it to the path.
Underfoot it is mostly gravel forest road: 4.6 km of the 9.0, with 3.4 km on a sealed surface and 640 m of narrower path. Nothing on the line is untagged, so this is a full picture rather than a partial one.
The Hennesee is a working water-supply reservoir — the Ruhrverband holds it to top up the Ruhr downstream, and since 2016 part of its water is treated for drinking. The level is drawn down accordingly: German Wikipedia carries a photograph of the lake half empty in October 2016. In a low year the shoreline the first two kilometres follow will sit well below the path. The bay at the start is one of two bathing areas on the lake that are free to use.