Open Water Safety: Dangers of open water

Why UK open water is more dangerous than it looks

Open water swimming in the UK is dangerous because cold water shock, sudden depth changes, strong currents and hidden hazards can overwhelm even confident swimmers within minutes, especially in rivers, lakes and reservoirs without lifeguard cover or clear safety information. These risks are often underestimated on hot days when the surface looks calm and inviting.

In 2024, there were 193 accidental water-related fatalities in the UK, according to the National Water Safety Forum, with May the single deadliest month for accidental drownings as warm air temperatures drew more people to the water.¹ Many of these deaths happened in inland waters – quarries, reservoirs, rivers and lakes – not at lifeguarded beaches. For children's homes and other residential settings, that makes local beauty spots and familiar rivers a critical safeguarding concern.

One of the biggest hidden threats is cold water shock. Anything below 15°C is classed as cold water; many UK lakes and rivers stay below 16°C all year round.¹ The RNLI notes that average UK sea temperatures are around 12°C, with many rivers colder still.² When a young person jumps or falls into that water, the sudden chill triggers an involuntary gasp, rapid breathing and a surge in heart rate and blood pressure. Even fit, confident swimmers can panic, inhale water or suffer a heart issue within seconds.

Recent incidents show that most tragedies do not involve planned, organised open-water swims. Between 2019 and 2023, about 41% of water-related deaths in England involved people who never meant to go swimming at all – they fell or slipped into deep water while near the edge.³ For staff planning trips with children and young people, that means risk assessments must cover banks, jetties, towpaths and quarries, not just designated swimming spots.

For residential children's homes, the real challenge is that these dangers are mostly invisible. Young people see clear water, warm weather and friends jumping in on social media. They do not see the cold water shock, the unseen drop-offs, or the parents, carers and professionals left behind when something goes wrong. Building this reality into keywork sessions, group meetings and activity planning is part of everyday safeguarding, not just a seasonal reminder.

Hidden hazards beneath the surface that catch swimmers out

The most dangerous open water hazards are the ones you cannot see: sudden shelves, underwater obstacles, reeds, machinery and steep, unstable banks that trap or disable swimmers before they can call for help. These risks exist in rivers, lakes, quarries, canals and reservoirs, even when the surface looks flat and safe.

Unlike swimming pools, open water is rarely uniform in depth. A young person can wade out in knee-deep water and, with one more step, find themselves in water over their head. Old quarry sites are notorious for vertical drops; reservoirs often have steep sides designed to hold water, not support swimmers. Once off the ledge, there are no steps or grab rails to help them back out. Even strong swimmers can be shocked by the sudden loss of footing and the cold at depth.

Vegetation and underwater structures add another layer of risk. Long reeds and weed beds can tangle around ankles, making it hard to kick or stand. Submerged tree branches, shopping trolleys, fence posts or discarded metal can cause serious cuts or snag clothing just below the surface. These are the hazards that rarely feature in generic water-safety posters, yet they are exactly what catch out overconfident teens copying stunts they have seen online.

Currents and underflows are just as deceptive. Rivers can run faster than they appear, especially after rain, pulling swimmers out of their depth or into obstacles downstream. Reservoirs and some lakes have hidden inlets and outlets where water is drawn in or released, creating strong undercurrents near towers, sluices and spillways. Signs may be small, vandalised or ignored. For anyone supervising children, the safest rule is clear: stay well away from any structure in the water, regardless of how calm it looks nearby.

The banks themselves can be treacherous. Loose stones, mud and algae make edges extremely slippery. A simple attempt to paddle, skim stones or take a photo near the water's edge can end in a sudden fall. In Bedfordshire alone, 24 people died in open water incidents in five years, with many cases linked to warm weather and informal visits to lakes and rivers.³ The majority were not organised events – they were everyday outings that turned in seconds.

For children's homes, it helps to make these risks tangible. Walk past a local river and point out steep banks, fast sections, weirs and overhanging trees. Talk through how difficult it would be to climb out in certain spots, or what might be hidden under cloudy water. Reframing familiar locations as environments that need active risk assessment can shift young people from thinking it's just a bit of fun to understanding this place demands respect.

How to talk to children and teens about safer choices

Talking to children and teenagers about open water safety works best when it is specific, honest and rooted in their real-world choices, not abstract rules or scare tactics. The goal is to help them recognise danger, plan safer alternatives and feel confident saying no to risky situations.

Start with what they already know: most young people have heard generic warnings about not swimming alone or avoiding alcohol near water. Build on that by introducing the lesser-known dangers – cold water shock, sudden depth drops, underwater entrapment and hidden machinery. Use real statistics, such as the 193 accidental water-related deaths in 2024,¹ and age-relevant case examples, focusing on decision points rather than graphic detail.

In keywork sessions, ask open questions: "If your friends invited you to a quarry on a hot day, what would you think about before going in?" Encourage them to identify red flags: no lifeguards, steep banks, signs of old industrial use, or murky water where they cannot see the bottom. Role-play responses they could use to push back on peer pressure, such as suggesting a supervised, lifeguarded swimming venue instead.

For group meetings in residential settings, co-create simple, visual rules with young people. These might include: only swimming at lifeguarded beaches or pools; staying away from quarries, reservoirs and weirs; never jumping from bridges or cliffs; and calling 999 and asking for the coastguard (at sea) or fire and rescue service (inland) if someone is in trouble. Reinforce the "Float to Live" message promoted by the RNLI: if they fall in unexpectedly, they should fight the urge to thrash, lie on their back, spread their arms and legs, and control their breathing before trying to move or shout.²

Staff training and supervision plans should reflect these conversations. Build water-safety checks into activity planning: map local high-risk spots, agree clear rules for unstructured free time, and document how staff will respond if young people head towards water on hot days. Share local authority or fire-service campaigns as discussion starters, especially around bank holidays and heatwaves.

1. National Water Safety Forum
2. RNLI – Cold water shock
3. BBC News – Bedfordshire open water warning