Sport England has confirmed that there has been a 245,000 drop of people participating in swimming over the last year.
The eight percent fall has significantly affected the sport, which was deemed the most popular in the country with 2.6 million people taking part weekly.
Sport England chief executive Jennie Price said: "I am disappointed with these figures, and I'm very concerned about the drop in swimming, which dominates the overall picture.
"If swimming's figures had been flat, we'd be looking at an overall increase in participation. I am encouraged by the fact that the current leadership at the ASA, and the wider swimming industry, now recognise there's an issue and want to work together to fix it. It needs to get on with it.
"Swimming has lagged behind running and the gym in terms of offering an attractive, modern experience to people who want to play sport and exercise. That has to change and to change quickly."
With regards to sport across the spectrum, 125,100 fewer people took part in a sport for 30 minutes once a week.
