Skip to main content
Home Secure area

River swimming dangers

Approximately 400 people drown every year in the UK. An analysis of recent annual accident data shows that of the 12 per cent of drowning victims who died while actually swimming, 7 people drowned in swimming pools, 11 in the sea, tidal pools and estuaries, and 7 in rivers, lakes, reservoirs or canals. In addition there were 8 who died swimming drunk, 30 who died through ‘jumping in’ to water and 17 who died in ‘jumping and diving accidents’. 95 per cent of all swimming drowning victims were male and many were teenagers.

Non-swimmers - Shallow water can deepen suddenly. If you, your children or your friends cannot swim make sure you scout out the extent of the shallows, set clear boundaries and keep constant supervision. Remember that even shallow sections of fast-flowing water can knock you off your feet. Be careful with inflatables, which can create a false sense of security and float off into deep sections or burst.

One of the most common dangers in outdoor swimming is slipping on rocks. Rocks are very slippery when wet and you don’t want to hit your head. Never run. Go barefoot to get a better grip or wear plimsolls with a rubber sole.

Hypothermia and cold-shock - Outdoor swimming in cold water saps body heat. 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. Press-ups, star-jumps and running up a nearby hill are the quickest! Wear a wetsuit if you want to stay in for more than a quick dip. ‘Cold-shock’ is the involuntary gasp and rise in heart rate that occurs as the body enters very cold water. Test the temperature and wade in slowly unless you are already acclimatised to outdoor swimming.

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, rubbish) may have been brought downstream or tipped in. A broken neck from a diving accident could paralyse you for life.
Cramps and solo-swimming - Swimming cramp can occur in the calf or foot and tends to be caused by overexertion, over-stretching and tiredness. If you get a leg cramp, shout for help, lie on your back and paddle back to shore with your arms. Swimming alone in deep water is foolish but, if you must, wear a life jacket or trail a float behind you on a cord.

Weeds - Most common in slow, warm lowland river swimming and lake swimming, weeds are quite easy to see and, while one or two aren’t such a problem, a spaghetti-like forest can entangle a swimmer’s legs. Try to avoid them. If you do encounter some, slow your swim speed right down, don’t kick or thrash, and either float on through using your arms to paddle, or turn around slowly.

Blue–green algae - In lowland lake swimming, after warm, wet weather, usually in late summer, algae can multiply and a powdery, green scum (the blooms) can collect on the downwind side of a lake. It’s obvious and unpleasant and can give you a skin rash or irritate your eyes if you bathe in it, and make you sick if you swallow it. Find a part of the lake without blooms or go somewhere else.

‘Swimmer’s itch’ (cercarial dermatitis) can be caught from contact with little snails that live on the reeds around marshy lakes and stagnant ponds. It creates a temporary but sometimes intense itching sensation that can last for up to two days. It’s not common, and requires no treatment, but it’s best to avoid wallowing in the bogs when outdoor swimming!

Weil’s disease - In urban areas sewers and storm drains may harbour colonies of rats whose urine may carry the bacterial infection Leptospirosis. Never swim in urban rivers, particularly canals, and be particularly cautious after heavy rains. If you are concerned about water quality cover any open wound with a waterproof plaster and keep your head (eyes, nose and throat) out of the water as much as possible.

Moving water and currents

Lots of our best water moves and river swimming in and against a current can be fun, just like swimming in seaside surf. However, you generally want to avoid being taken downstream in an uncontrolled manner. Even shallow water, if it’s moving fast enough, can knock you over and carry you away. Always consider: if I do lose my footing or get swept downstream, where will I get out? Identify your emergency exits before getting in and scout around for any downstream hazards (obstructions, waterfalls or weirs).

When judging flow rates remember the basics: the shallower or narrower the river bed becomes, the faster the water must flow to pass through, and vice versa. That’s why ‘still waters run deep’. Throw a stick in the water to judge flow speed and avoid anything moving faster than you can swim. In tidal estuaries there can also be counter-flows, with seawater moving in and river water moving out. In deep rivers or gorges the water in the surface layer may be flowing more slowly than the water beneath.

These confused waters aren’t necessarily dangerous or outdoor swimming – you’re not going to be sucked under – but they can be disorientating and may take you out into deeper water or close to an obstruction. You can generally feel what’s happening under the water with your feet and body. Large eddies and surface ‘simmering’ also suggest something more powerful is happening beneath. Be particularly cautious in these unpredictable waters.

Click on the link below for RoSPA's advice on Water Safety for Children and Young People:

Water Safety for Children and Young People