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Open water swimming safety – essential tips for wild swimming

Open water swimming brings a great sense of freedom and connection to the outdoors. But that also means there are additional risks beyond those you'd encounter in a pool environment, that you need to take into consideration. Top level Masters swimmer and open water expert Helen Gorman shares some tips to help you stay safe when you're swimming in open water.

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Want to enjoy the freedom of open water swimming? Swimming in outdoor natural environments is a totally different experience to swimming in a pool. No two swims are ever the same.

Swimming in lakes, rivers and seas can improve your cardiovascular fitness and promote better mood. It may be even more beneficial for fitness than pool swimming if you consider the extra endurance, strength and skill that’s needed to swim in rougher conditions. And being immersed in nature is a wonderful experience that draws people to the water.

The benefits of open water swimming for mental and physical health are wide-ranging – as long as you follow a few basic (yet essential!) safety tips. We take a look at some of the risks to take into consideration when you’re swimming in the great outdoors, and share some tips to help you stay safe and ensure every swim is a great experience.

What are the risks of open water swimming?

Open water swimming is an incredible sport, but everyone should plan and mitigate against the risk of drowning. Factors to consider include the unpredictability of water and weather conditions, cold temperatures, poor water quality and poor visibility. There is also the possibility of overexerting yourself as open water swimming can be significantly more demanding than pool swimming.

A sobering statistic is that globally, drowning is the third highest cause of unintentional death, with 236,000 drowning deaths per year according to the World Health Organisation. Many who drown will have been capable swimmers that got into unexpected difficulties.

Let’s take a look at some of the main risk factors when it comes to swimming in open water, and how to mitigate against them.

Water conditions

Swimming in familiar or managed locations is significantly safer than swimming without lifeguards or somewhere new for the first time. If you are sea swimming, research the tides, currents, waves and temperature. Surfing specific websites often offer very detailed information. You can also choose to swim on lifeguarded beaches, close to a lifeboat station or coast guard look out point for extra safety.

Tide times are hugely important. Swimming with an incoming tide is safer than an outgoing one. Swimming around high tide is usually a better experience than low tide as you will be closer to the shoreline. Be mindful of where you leave your clothes and belongings if the tide is coming in!

Open water swimming in a Sumarpo wetsuit
Choppy water or strong tides can make swimming in open water a lot more taxing, so be mindful of the conditions.

Tides and currents also affect rivers by increasing water levels and flow speed, as does heavy rain. Avoid river swimming after heavy rain as water quality can be impacted by run off from local fields, including agricultural waste and pollutants.

If you’re visiting a lake, it’s important to know how deep it is, as this will impact safety as well as temperature. Make sure you know where the safest access points are, and where you can exit the water if you need to get out before you’ve finished a full lap. Many venues will also display the water temperature, which you can use to help you decide what gear you need and how long you should stay in the water.

Managed venue or not, wearing a wetsuit is always a good idea to give you extra warmth and buoyancy. As is using a brightly coloured tow-float or swim buoy to increase your visibility and safety – particularly if you’re swimming in water shared with boats, paddle boarders and other water-users.

Weather conditions

Weather conditions can change rapidly, and swimmers are exposed and vulnerable in the water. Actively seeking out a clear sunrise in summer or bright blue sky to float under can make your swim magical, but bad weather can mean you don’t end up getting in at all. Find a detailed and reliable source of weather information at the precise location you are visiting (the basic apps on most smart phones are not as accurate as you think!)

Don’t swim during a thunderstorm and when there’s fog or high winds. Even swimming after a storm has passed can present hazards including floating debris, pollution and murkier, faster flowing or deeper water.

Swimming during winter has become very popular, but cold water swimming is not the same as open water swimming. It has its own set of safety considerations.

Fatigue and over exertion

Open water swimming is physically demanding as you are potentially swimming longer, uninterrupted distances in more challenging conditions. And unlike in a swimming pool, where you can get out almost immediately if you start to feel overly fatigued. In open water you may have at least a few hundred metres to swim before you’re back on dry land.

This is why it’s important to always swim within your own capabilities – both in terms of the pace you swim, and the amount of time you spend in the water. Build up the duration and intensity of your swims very gradually. Ensure different ability levels are catered for if you’re swimming with a group, and don’t be afraid to speak up if the pace is too fast. If you start to feel dizzy, confused or tired get out of the water immediately and get yourself dry and warm.

sea swimming sumarpo wetsuit
Swim within your own limits to make sure you always have enough energy to get safely back to shore.

Getting a muscle cramp may seem relatively insignificant in some scenarios, but in open water it can be much more serious if it prevents you from swimming back to safety. Be mindful of your overall health, fitness and hydration, too. If you are generally not feeling well, don’t go.

It’s also a good idea to wear a watch so that you know how long you have been in the water for. It doesn’t have to be a GPS watch – though these are handy to track our progress – it just needs to be waterproof and tell the time.

A coached or group session is the safest environment. If you visit a wild swimming location, take responsibility for your own health and safety by selecting familiar venues and having at least one buddy with you as well as a mobile phone with a good signal.

Hypothermia and cold water shock

Hypothermia and cold water shock can be avoided by being physically and mentally prepared. Getting in gradually, splashing your face with cold water and pouring water down your wetsuit in advance (if wearing one) will also help.

When it comes to cold water swimming, there’s a misconception that the temperature of the water in Celsius dictates how many minutes you can spend in the water. For example, if the water is 10 degrees Celsius you can tolerate it for 10 minutes. This idea is wrong, because everyone is different. 10 minutes would be far too long for some, while perfectly fine for others. Understand your own body and capability by starting with shorter swims and building the length and distance of your swims gradually.

Have dry, warm clothing to change into as quickly as possible after swimming – even in summer. Choose baggy clothes that are easy to get on so you can get into them quickly. It is possible to become hypothermic whilst swimming in any water that is cooler than body temperature, so that includes heated pools and lidos as well open water locations during the summer.


Safety equipment for open water swimming

A brightly coloured swim cap is essential for you to be seen and a tow-float will increase your visibility from land. Wearing a wetsuit is significantly safer than not wearing one as it provides buoyancy as well as warmth, but not all open water swimmers wish to wear them.

A mobile phone with a good signal is essential, even if it’s not with you in the water, you need a way to communicate with the emergency services should it be necessary. A GPS watch isn’t essential, but many have an SOS feature that will trigger if you get into difficulty. It’s a good idea to wear a watch – even if its just a basic waterproof watch – so that you know how long you have been in the water for and you can make sure you’re swimming within your limits.

Read our essential open water swimming gear guide for more advice on what kit you need.

What are the negatives of wild swimming?

The key risk when taking part in wild swimming is the lack of supervision and the potential remoteness of the location. Should you be unfortunate enough to get into difficulty, getting help may not be quick or easy. There are various water, weather and wildlife factors to consider as well as legal implications of accessing water that may be private.

How safe is wild swimming?

Whilst there are risks involved in wild swimming, you can take precautions and enjoy it all year round. Safety depends on your choice of location and how experienced and prepared you are.

 What are the risks of open water swimming?

The most significant risks of open water swimming include hypothermia, waterborne illness, accident and injury or drowning. With preparation and planning, the risks are significantly reduced.

What are the top safety tips for open water swimming?

The top safety tips for open water swimming are to swim with a buddy or group, be visible, know your limits and fully assess the water and weather conditions before you get in.

How do you stay safe in open water?

Regularly assess changing water and weather conditions; be aware of your surroundings; be visible; stay hydrated and don’t exceed your own capabilities.

Is it safe to swim in the sea?

The sea is very unpredictable. You need to use good judgement and be very aware of your surroundings and capabilities. Note that swimming with an incoming tide is safer than an outgoing one and it’s safer to swim parallel to the shoreline rather than away from it.

Is sea swimming good for everyone?

Sea swimming is beneficial for many people but may not be suitable for everyone. It’s essential to make an accurate judgment of ability, fitness, and confidence. If you’re in any doubt, consult a health care professional, a swimming instructor or organised group.

Helen Gorman
Written by
Helen Gorman
Helen is part of the editorial team at TRI247 after spending ten years as a Press Officer with British Triathlon. She's mostly found at a pool, sometimes breaking world masters records.
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