The Alfsee flood retention basin was created in the 1970s to prevent flooding. The area is designated as a EU bird sanctuary. It consists of a main basin and a reserve basin to the north, which is much more natural. The main lake is also heavily used for tourism. The most recommendable is the visit in winter, when masses of water birds like Northern Shoveler, Tufted Duck, Eurasian Wigeon, Goosander rest here. The lake is large and would certainly also be suitable for loons and sea ducks. In 2020 a Pygmy Cormorant visited the area.
There are plenty of parking spaces around the lake. The best way to get around the lake is by bike. The Rieste train station is nearby. The route that is shown on the map below has a total length of 15 km.