1 . For 365 days a year, come rain or shine, Ruth Rose, 87, has taken a morning swim in Seaford, a small coastal town on the south coast of England. What started as a personal habit has developed into an almost full-time occupation（工作） over the past eight years, with Rose gathering a group of over 150 swimmers each day.

“It's a social event of the day,” she said. “The community needs this sort of grouping of people. We're doing something together and making our lives better.” Rose's group, called the Seaford Mermaids, has grown in number since last year.

While cold water swimming is nothing new in the U.K., its popularity has grown massively over the past few years. According to a recent nationwide study of the popularity of open water swimming, 7.5 million swim in outdoor pools or open water every year. 2.1 million of those say their preference is to swim in cold water. And supporters say swimming in cold water isn't just a form of exercise.

Jo, a recent addition to the Seaford Mermaids and one of the younger members of the group, lost her job last summer. She said that after being encouraged by a friend, swimming each morning had made a “huge difference” to her life.

“While precautions (预防措施) must be taken, especially for first-timers, to enter the water slowly and be well aware of an exit strategy in case muscle movements slow down in the cold water, there may be some potential (可能的) benefits of cold water swimming in treating anxiety and depression（抑郁), though the science is still unclear,” said Dr. Heather Massey, a senior lecturer at School of Sport Health and Exercise Science, University of Portsmouth.

“One of the ones that is a bit of a hot topic at the moment is that it may have some potential health benefits,” Massey said. “This is a hugely under-researched area and there's lots of anecdotal(传闻的) 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.”