Winter Wild Swimming Guidance in Lochs and Rivers

For many of us, inland wild swimming doesn’t stop when the temperature drops—it simply changes. Winter swimming can be deeply rewarding, but it asks something different of us: preparation and respect.

Whether this is your first time dipping in winter, or if you are a seasoned dipper, equipping yourself with good information is part of getting ready for each swim.

Understanding the Cold

Hypothermia is a real and serious risk for swimmers. It occurs when your core body temperature drops below 35°C (normal is around 36–37°C).

If you’re walking, talking, and thinking clearly, when you exit the water your core temperature is at a safe level.

That said, what matters most is what happens next.

Afterdrop: The Hidden Risk

Afterdrop is when your core temperature continues to fall after you leave the water, often for 20–40 minutes.

You might experience:

Intense or prolonged shivering

Feeling woozy, nauseous or exhausted

This is why getting dried and dressed quickly matters so much. Lingering in wet clothes, chatting, or packing up slowly increases risk. Winter swimming rewards efficiency and I suggest warming up your core first by drying and pulling several layers onto your top half, pop on a woolly hat and I suggest my secret weapon of a hot water bottle tucked into the pouch of my hoody or somewhere similar.

Then onto the easy to pull on trousers, warm socks and boots.

If after drop hits you hard, please learn from this and  reduce your time in the water next time.

Why Hypothermia Matters

As core temperature drops, the risks escalate:

Loss of coordination and mental clarity

Irregular heart rhythms

In severe cases: cardiac arrest and death

This isn’t about fear—it’s about facts. Inland waters may look calm, but cold affects the body quietly and quickly.

Temperature Is Personal — Not a Competition

You may hear people say things like “7 or 8 degrees isn’t that bad.”

The truth? Cold tolerance varies hugely.

Water around 7°C is very cold and edging towards ice swimming territory, which normally requires structured preparation, support, and experience. Medical oversight is often used at those temperatures for good reason.

As a general guide:

Below 15°C: Cold

Below 10°C: Very cold

Below 5°C: Extreme / ice cold

But water temperature is only part of the picture. Wind chill, air temperature, how you’re feeling that day, hydration, nutrition, body composition, and even stress levels all play a role.

Ignore bravado or what everyone else is achieving. Listen to your body.

Go Slow, Stay Cautious

Humans are not cold-blooded. While we can adapt over time, adaptation never removes the risk of hypothermia and cold water shock—it simply shifts your tolerance.

Early signs that it’s time to get out include:

Shivering

Loss of dexterity in hands or feet

Ideally, you exit before these symptoms kick in. The goal is to get out feeling good, not depleted.

Reduce time as winter deepens

Increase time cautiously as temperatures rise again

There is no evidence to support the old “one minute per degree” rule. For many people—especially beginners—that could be far too long.

Inland Water Comes With Its Own Considerations

In rivers, lochs, and reservoirs water levels can rise quickly after rain. Currents may be stronger beneath the surface than they appear. Exits that were easy in summer can become slippery or inaccessible in winter.

Always consider:

Recent weather and rainfall

Water flow and hidden currents

Entry and exit points

Ice at the edges or underfoot

What looks serene can change fast.

If You Dip

Don’t swim alone—go with others who can keep an eye on you and visa versa and do give  a helping hand when needed

Keep it short and get out early

Wear appropriate kit if you need it (wetsuit, boots, gloves, bright cap)

Choose safer locations with easy exits

Never mix cold water and alcohol

Don’t push through shivering or numbness

And remember: cold water shock can affect anyone, even confident swimmers. A “quick dip” can become exhausting or disorientating far faster than expected.

If Something Goes Wrong: Float to Live

If you or someone else gets into trouble:

Roll onto your back, ears in the water

Stay calm and focus on breathing

Gently move hands and feet—starfish style

Don’t worry if your legs sink

Raise a hand and call for help

If you see someone struggling: call 999 or 112, ask for the Fire & Rescue Service (for inland waters), and encourage them to float on their back