Around 4,000 amateur and professional swimmers were registered to take part during the two-day annual Christmas Cup in Geneva — an all-time record since the event was first held in 1934.

“Every year, we shatter the record,” Christophe Jacot, head of the organising committee, told AFP.

“Here, we are talking about 4,000 swimmers. There is just more and more interest,” he said, pointing out that “there are already waiting lists for the 85th edition” next year.

On Saturday morning, throngs of men and women wearing butterfly wings, Venetian masks and colourful wigs, ran down a ramp towards the pier into the murky green water.

Some guzzled champagne straight from the bottle before taking the leap.

The swimmers were asked to swim a total of 100 metres (328 feet) — a chilly feat with the temperature in the air at -2 degrees Celsius (28.4 degrees Fahrenheit), while it was 8.8 degrees Celsius in the water.

“It was good in the water,” said swimmer Frederic, who — like his entire team — was dressed in a yellow costume of a “Minion” film character with long, dark braids protruding from his yellow swim cap.

“But when you get out, with water on your clothes, it’s not great.”

Jacot acknowledged that the temperature difference can cause a shock to the system, but insisted “it is safe. You are not swimming alone.”

“Breath in, breath out, take it slow,” he recommended, adding that anyone who has a problem can simply “raise their hand, and boom, we will come and pick you up.”

A group of women dressed as pharaohs warmed up in a hot tub after their swim, sipping champagne and eating oysters.

Saturday marked the tenth time their team participated in the swim, and they knew it was important to “sustain yourself after the race, to get your strength back.”

“We have experience,” one of the women said, describing Saturday’s event as “pure bliss”.