guide

Cold water safety: what every swimmer should know

RNLI and Outdoor Swimming Society guidance on planning for cold water and responding if you get into difficulty.

Cold water can affect your breathing and movement, including in summer. Open-water conditions also include hazards that vary by site, such as wind, waves, currents and difficult exits. Treat every swim as a fresh decision.

Before entering

Check conditions and local warnings; choose an entry and exit you can manage; swim with others; tell someone your plan; and carry a way to call for help. Enter gradually and do not jump or dive into cold water. Wear visible swimwear and stay within your ability.

If cold water shock catches you

Follow RNLI Float to Live: lean back, extend your arms and legs, and try to control your breathing. Float until you can breathe more normally, then call for help or consider your next move. Do not fight the water with frantic swimming.

There is no universal safe duration. Cold, weather, health, exertion and individual response all vary. For a coastal emergency, call 999 or 112 and ask for the Coastguard. This page does not replace emergency or medical advice.