When Switzerland's first mixed bathing area opened at Weggis near Lucerne in 1919, the authorities had to ban hobby photographers from taking pictures.
They may have been a nuisance to people enjoying recreation and relaxation at the lakeside, but the resulting pictures today offer a fascinating glimpse into bathing in times gone by.
The photographs form part of the current "Lust for the Lake - Public Baths in Lucerne" exhibition at the central Swiss city's Museum of History.
Museum director Heinz Horat said that the Weggis baths proved very popular in their first season.
"From July to September 1919 there were around 33,000 people coming to the baths, of them 18,000 bathing and around 15,000 just looking," he told swissinfo.
Some pictures show quite clearly people standing around in early swimming costumes, with fully clothed observers sitting in the background.
"Some came of course to look at the ladies and gentlemen and then there was the problem of people taking photos," Horat explained.
"We have lots of good pictures now but it became a problem for bathers, and the authorities decided not to allow photographers any more - to let people have some privacy."
The mixed Weggis baths were quite a daring concept for the time. But it was just after the First World War and tourism was slow. Times were also changing.
At first critics thundered that the baths were immoral, but police inspections reported no problems at all. People seemed to be enjoying their newfound bathing freedom.
In the 19th century, lake bathing was a way of keeping clean, as most houses did not have bathrooms.
As the health and wellbeing movement took off, taking a dip also became popular, but the sexes were strictly separated. Swimming also made waves, but only for men.
As some of the original bathing outfits on display show, women would have struggled to move around in their two-piece woollen costumes – trousers and a dress on top down to the knees – that weighed up to five kilograms when wet.
Men had a rather more streamlined outfit, based on male underwear of the time. Bathing wear later became skimpier and men wore trunks.
"But then with the opening of the baths in Weggis, with men and women together, the authorities decided that men had to wear a bathing suit covering the upper part of the body," said Horat.
Bathing was an accepted pastime by the 1920s. Posters, some of which are on display, advertised lakeside beaches. It had become a social event, and with this – inevitably of course – came bathing fashion.
"Usually from this period you have black and white photos so you get the impression that all the suits were dark, but you can see from our examples that they were coloured, with red and white stripes, or in pinks and greens," Horat told swissinfo.
A matching little cap was de rigueur and the modern woman also had so-called "beach pyjamas", for out of the water.
In the 1940s ladies' swimming costumes became fitted, and two-piece suits from the United States also gained acceptance.
But it was the arrival of the bikini in France in the late 40s – named after the Pacific atomic tests of the time – that really caused a stir.
French actress Brigitte Bardot helped popularise it and by the time Swiss actress Ursula Andress strode out of the sea in her cream bikini in the James Bond film Dr No in 1962, it was firmly established.
Swiss companies, such as Lahco, took the plunge. In its heyday, the 1950s-70s, it was the most successful Swiss swimwear brand in Europe. And, as some of its current collection on display shows, the retro look is very much "in" this year.
Bathing areas have also changed over the years. The first were fenced off using wooden palisades. Men had bigger pools than women and were allowed to jump into the lake. Washing areas were partitioned off at the sides.
One curiosity is the "Mississippi steamboat", as it was known locally. This huge floating building, built in the middle of the river in 1868, had hot water and could be used for personal and clothes washing.
"It went on until 1971 and then it was destroyed, but for 100 years many people enjoyed their baths there," Horat said.
After Weggis came the Lucerne Lido, named after the famous Venice beach of the same name, to give it a glamorous appeal.
Lake bathing continued to be popular throughout the 20th century, although as photos attest, pollution became a problem. The lake was eventually cleaned in the mid 1970s.
Although some of the old baths have now disappeared, people still have a large choice of areas around Lake Lucerne, including Weggis. In summer thousands of Swiss still head to the water.
"We have many lakes in Switzerland and many people just have a few hundred metres to go to the beach. What is good is that we don't just have official baths but we still have many beaches open to the public," said Horat.
swissinfo, Isobel Leybold-Johnson in Lucerne
The Lust for the Lake – Public Baths in Lucerne exhibition runs until August 31, 2008 at the Lucerne Museum of History.
The exhibition is set out like an old-fashioned lakeside bathing area. Around 50 curtained cabins can be opened, each revealing a different aspect of Lucerne bathing history. This includes many photos, several home films, as well as objects and clothing, including a beach bride's outfit.
The opening hours are Tuesday-Sunday: 10am-5pm. It is closed on Mondays.
The first bikini, created by Frenchman Louis Reard, made its debut in 1946. Its name came from the fact that it was launched shortly after the first US post-war nuclear tests on the South Pacific Bikini atoll.
At first it was difficult to persuade the public that it was acceptable for "decent" women to wear it. But Brigitte Bardot sparked the French craze for the skimpy garment and by the 1960s its popularity had spread to most countries.
In 1962 Swiss actress Ursula Andress made cinema history as Honey Ryder in the James Bond film "Dr No" by emerging from the waves in a cream-coloured bikini. It was sold at auction for more than £35,000 ($85,050) in 2001.