What are the dangers of open water swimming in winter? What do you do to avoid them?
You can wear a wet suit or a dry suit. When you first try it, have a boat go along with you, or swim very near the shore. You will likely want a hood, gloves, and boots.
If you swim unprotected in cold water, you can get hypothermia, you muscles can essentially stop working, and you can drown. It's not possible to generate enough body heat to maintain your body temperature when swimming in very cold water without protection.