Cold water swimming: The outdoor pursuit making waves in the UK

BRIGHTON -- For 365 days a year, come rain or shine, Ruth Rose, 87, has taken a bracing morning swim in Seaford, a small coastal town on the south coast of England.

In remarkably good health for someone her age, what started as a personal pursuit has developed into an almost full-time occupation over the past eight years, with Rose marshaling a group of over 150 swimmers with weather reports each day.

"It's a social event of the day," she told ABC News. "The community needs this sort of grouping of people, people thinking here we are together. We're doing something together and making our lives better."

Rose's group, called the "Seaford Mermaids," has grown in number since the start of the coronavirus pandemic. With Brits starved of the usual opportunity to go outside during the first lockdown, the outdoor activity was one of the few reasons people could legally leave their homes, and their membership almost doubled.

While cold water swimming is nothing new in the U.K., its popularity has grown massively over the past few years. Every few weeks in the British press there seems to be a new article about the experience of taking a plunge into freezing open water, with Brits in ever increasing numbers taking to the seas and lakes alone or in groups.

According to the most recent nationwide study of the prevalence of open water swimming in 2017, 7.5 million swim in outdoor pools or open water annually. 2.1 million of those say their preference is to swim in open water.

"I think definitely over the last few years, cold water, open water swimming has increased in popularity," Dr. Heather Massey, a senior lecturer at School of Sport Health and Exercise Science, University of Portsmouth, told ABC News. "And also, again, this year has been a step change upon that as well."

And advocates say swimming in cold water isn't just an invigorating form of exercise.

Jo, a recent addition to the Seaford Mermaids and one of the younger members of the group, lost her job in the summer due to the coronavirus pandemic. She told ABC News that, after being encouraged by a friend, swimming each morning had made a "huge difference" to her life.

While precautions must be taken, especially for first timers, to enter the water slowly and be well aware of an exit strategy in case muscle movements slowdown in the cold water, "there may be some potential benefits to cold water immersion" in treating anxiety, depression and PTSD, though the science is still unclear, Massey said.

"One of the ones that is a bit of a hot topic at the moment is that it may have some potential health benefits," she said. "Now, at the moment, this is a hugely under-researched area and there's lots of anecdotal evidence that may support an improvement in people's health and well-being, whether that's physical or mental health. However, we don't have the scientific evidence to support that yet."

A recent study by researchers at Cambridge University found that a certain "cold shock" protein was discovered in cold-water swimmers at a London pool, which could help create new treatments for dementia.

While advocates swear by the benefits of cold-water swimming, in the case of the Seaford Mermaids it has helped the community rally around a daily routine, giving them a new meaning in life.

"It's a pioneering social experiment that can be left to posterity so that posterity learn something about how to grow older and feel good and not be lonely and not be isolated," Rose said. "I'm very pleased that the world is waking up to it."