520 people entered the Coniston Chill Swim this year. Last year, the first year of the event, saw 220 compete.
The race takes in the length of Coniston: 5.25miles.
The fastest are in the water for 2 hours. The slowest take 5 and a half hours to complete it. The average swimmer does it in 3 and a half hours.
It's a long distance swim and a quarter do it without a wet suit. The temperature in there is 17.3 degrees Celsius.
Many arrive having never swum this far before. They'll leave Cumbria knowing they can.