The Rotsee (previously known as Rootsee) is a natural rowing lake on the northern edge of Lucerne, Switzerland. It is regarded as one of the best rowing venues in the world. Description and location The lake and its surrounding area is used for local recreation. All of the lake frontage is a protected area. The lake formed through glacial processes and it is thought that the river Reuss flowed through this valley in between ice ages. There is no notable inflow and virtually no current. Nearby hills protect the lake from wind. It is long. These factors make it an ideal rowing venue and German-speaking rower refer to it as Göttersee, which translates as "lake of the gods". The expression was coined at the 1962 World Rowing Championships by a Japanese rowing official. The Zug–Lucerne railway is located north of the lake. The south side of the lake has residential land use. The Ron is a creek that is the lake's outflow; it flows into the Reuss at Root. History Since 1885, the Rotsee was used for ice cutting, which was stored in insulated cellars lasting until autumn. Up to 80 people were employed, with the ice used by the hotel industry and brewers. This business ceased during the 1910s when refrigerators became more economical. With its proximity to Lucerne, the Rotsee and its surrounding area has been used for local recreation since the mid 18th century. An army ammunition depot next to the Rotsee exploded in 1916, resulting in five deaths and thousands of grenades being thrown in the lake. Recreational divers spotted some grenades during the 1970s and Police divers have since recovered about 1000 grenades from the lake. Police and army last found grenades in 2020 and it is assumed that there are still more explosives in the lake. Increasing housing in the area, with sewage discharge into the lake, resulted in ecological decline. The sewage treatment plants built at the lake in 1922 and 1929 belonged to the first installations in Switzerland, but the tension about ecological decline peaked in the 1920s. This gave rise to the founding of a society Gesellschaft Pro Rotsee in 1929 with the aim of saving the lake. In 1922, a canal was built that diverted water from the river Reuss into the Rotsee, but since the Reuss was also polluted, this did not significantly improve water quality. Significant improvements were