Top 10 tips for safe wild swimming

Daniel Start, author of brand new guide book 'Wild Swimming France', gives his top tips for staying safe in the water, at home or abroad

8 mins

Wild swimming is the traditional art of swimming in natural bathing pools, such as rivers, lakes and waterfalls. France and UK both have these in abundance, and have some of the most beautiful and diverse landscapes in Europe. Taking an al fresco dip is the essential way to stay cool in summer, and the highlight of any holiday.

Like cycling, hill-walking, canoeing and many other outdoor activities, wild swimming has some inherent risks and dangers but with the right preparation and information you can stay very safe, without losing the sense of adventure.

1. Non-swimmers and children

Take special care with children and non-swimmers near water. Even shallow water can suddenly deepen. If you, your children or your friends cannot swim, make sure you scout out the extent of the shallows, set clear boundaries and maintain constant supervision.

Remember that even shallow sections of fast-flowing water can knock you off your feet. Be careful with inflatables: they can create a false sense of security and float off into deep sections or burst. Swimmers lacking confidence should always stay close to the shore.

2. Slips, trips and falls

It sounds obvious but this is the most likely hazard while clambering around in rivers and waterfalls. Never run or rush and wear plimsolls or jelly shoes with a rubber sole. If you enjoy more serious scrambling and climbing along rivers why not join an aqua randonnée or canyoning course (in France) or coasteering or ghyll scrambling course (in the UK)?

3. Cold water

Summer swimming in southern France is rarely cold, but out of season, or in mountain lakes or streams, or in most of the UK, the water can be bracing. Swimming in cold water saps body heat fast so don’t stay in too long (20 minutes is ample). Shivering and teeth-chattering are the first stages of mild hypothermia, so get out of the water and warm up with a combination of warm, dry clothes and activity.

4. Jumping and diving

Always check the depth of the water, even if you visit the same spot regularly. Depths can vary and new underwater obstructions – sand, rocks, branches and rubbish – may have been brought downstream. Never judge water depth by just looking. A broken neck from a diving accident could paralyse you for life.

5. Cramps and solo-swimming

Swimming cramp can occur in the calf or foot and tends to be caused by over-exertion, over-stretching and tiredness. Cramp, contrary to popular belief, is not more likely to happen after eating but being dehydrated, or a poor diet in general, can make you especially prone.

If you get a leg cramp, shout for help, lie on your back and paddle back to shore with your arms. For these reasons swimming alone in deep water isn’t a great idea but, if you must, trail a float behind you on a cord.

6. Weeds

In slow, warm lowland rivers and lakes, weeds are quite easy to see. While one or two don’t present a problem, a spaghetti-like forest could entangle a swimmer’s legs, especially if they start thrashing about. Try to avoid weedy areas, but if you encounter some, don’t panic, just glide through them using your arms to paddle.

7. Blue-green algae

In lowland lakes polluted with fertilizers, algae can multiply after warm, wet weather, usually in late summer. This results in a powdery, green surface scum (the blooms) on the downwind side of a lake. Its presence is obvious and bathing in it can bring on a skin rash, irritate your eyes, and make you sick if you swallow the water. Find a part of the lake without blooms, or if there isn’t one, don’t swim.

8. Currents

Swimming with or against a current can be fun, just like swimming in seaside surf, but losing control and being carried downstream can be dangerous. In fast-flowing water always think about where you will be able to get out if you lose your footing. Identify your emergency exits before getting in and scout around for any downstream hazards (obstructions, waterfalls or weirs).

In canyons, bear in mind that as the gorge narrows the water will deepen and increase in flow. Always explore canyons from the bottom up, so you can ensure there is a safe route back down again. Never enter a canyon if a thunderstorm is expected upstream.

9. Flooding and dam releases

This is less of an issue in the UK but France has a large number of hydroelectric dams. These need to vary their release rates in order to meet changing electricity demands and you will see very clear yellow EDF (Électricité de France) signs along the river where this is the case. In reality, flow rates are generally constant during the summer when electricity demand is highly predictable and many local people swim without concern.

Changes in flow rates are usually pre-planned and canoe companies are often notified so have more information. Even if EDF do need to increase flow, changes are not tsunami-like – water levels will usually increase up to about 30cm over 15 minutes. The main advice is to avoid picnicking on river islands that could be cut off, and keep an eye on children playing close to the shore.

10. Access and private property

In most countries, if there is public access to the bank, no one is likely to stop you from swimming, apart from a grumpy angler. In France the general rule of thumb is that fisherman have access before 10am and after 6pm, and that canoeists and swimmers use the river during the daytime.

In open access areas (eg. national forest, highlands in National Parks) access is much more relaxed. Note that wild camping – although tempting – is illegal in France and most of the UK. If you do want to camp wild, avoid farmland, never light fires, pitch late, rise early and take absolutely everything away with you.

Wild Swimming France by Daniel Start is published by Wild Things publishing and is available from

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