The origin of the beach area, however, goes back to the beginning of the 1900s. The city of Berlin had, since the unification in 1871, experienced enormous growth, both in population and in new buildings. Large housing projects were planned and realized and these squeezed the working population tightly together in small apartments with little light and less fresh air. Therefore, people tried to escape into nature when they had the opportunity. Favorite escapes for those who could not afford to go on holiday to the Baltic Sea were the nearby lakes. Particularly suitable was the Wannsee with its wide, shallow and sandy eastern coast.
Due to the moral standards of the time, public bathing, especially with women and men together, was illegal. In 1907, the administration of the Brandenburg Teltow district southwest of Berlin, then the known authority over the area, gave in to public pressure and officially allowed bathing on a 200-meter stretch of beach. Behavior was strictly regulated, down to details of dress laid down by police regulation.

Strandad Wannsee

Construction began on May 8, 1907. In 1909, a lease was signed between the royal government and a local businessman, Frankenthal from Nikolassee. Freibad Wannsee, as it was called, then consisted of one beach each for men and for women, both 65 meters long, separated by the family section, which offered 350 meters of beach. The sections were separated by planking. Tents, erected at the foot of the steeper slope towards the forest, served as changing facilities.

After the First World War, the importance of the beach increased, not only among the people of Berlin, but also for the surrounding communities. After the end of the private lease, the municipality of Berlin took over, and the company became part of the municipal forest service, due to its location in Grunewald. In the same year, 1924, the tents were replaced by thatched pavilions and the previously lacking sanitary facilities were improved. The area was extended to 800 meters and was open year-round, making the facilities available to winter bathers and skaters. Attendance increased, especially after the S-Bahn from nearby Potsdam to Erkner was opened. One year there were 900,000 visitors.