For those who like to take things to the extreme there is such a thing as an Ice Mile. This challenge was created by The International Ice Swimming Association https://www.internationaliceswimming.com
There are many criteria to completing an ice mile but basically-
find body of water that is a least 25 mtrs in length and 5 degrees or under in temperature
swim 1 mile
After three winter seasons training I had a go in 2018 and became one of the 70th something women in the world to complete one…the achievement still makes me smile.