Taking a dip in outdoor pools has a tradition in Switzerland going back 200 years. It's a custom that begins anew every May.
In the 19th century, the authorities in Swiss towns began to regulate their citizens' love of stripping off and swimming in the local lakes and rivers. They began erecting wooden structures on the water's edge to separate the sexes.
In Zurich, a bathhouse for women was built on the Limmat River in 1837. This "Frauenbad" still exists.
A men's bathing area was built along the old city walls in 1864, and continues to be in operation and reserved for men only.
One of the first outdoor swimming baths for both men and women, Weggis-Lido, was built in 1919.
In the 1930s, numerous public baths were built, and in some cases as a way to create jobs during the economic downturn of the decade.
In our series #swisshistorypics we look back on some of the earliest bathing bathing establishments in Switzerland.
(Photos: Archive of Building History, ETHZ library, Picture Archive)