From rivers and reservoirs to the ocean itself, our open waters are becoming increasingly popular places to swim. If you are one of those taking the plunge and enjoying the health and well-being benefits of open water swimming, it’s important to make sure that you enjoy the water safely. Take a few minutes now to read our tips and recommendations; it could save your - or someone else’s - life 

Here are just a few reasons why people report loving a dip outdoors: 

  • Improves Fitness Levels and Metabolism: regular cold water swimming can boost your fitness.
  • Relieves Aches and Pains: cool water can help alleviate muscle soreness and joint pain. 
  • Enhances Circulation: cold water immersion may improve your blood circulation. 
  • Boosts Your Immune System: exposure to cold water may strengthen your immune response. 
  • Supports Mental Health: many people report that cold water swimming helps manage stress, anxiety, and depression. 
  • Builds Friendships: you can meet fellow swimmers and be part of a supportive community. 
  • Provides a Natural High: the exhilaration of a cold water swim can leave you feeling awake and energised. 
  • Connects Us with Nature: it's a wonderful way to enjoy and appreciate the great outdoors. 

It’s clear that swimming outdoors can be an amazing experience, but it’s also far riskier than swimming in a supervised indoor pool. In the past five years, nearly a quarter of all accidental drownings have occurred when swimming at open water sites, either inland or along the coast. While this represents only a small fraction of the estimated 4.1 million people who swim outdoors, many of these lives could have been saved with some basic knowledge and understanding of open water safety. By learning the basic principles of safety and recognising hazards, you can enhance your enjoyment of open water activities and be part of the movement to significantly reduce the number of incidents and accidents each year. 

Whether you're a confident outdoor swimmer, just moving from the swimming pool to open water, or simply enjoying a quick dip, take a moment to read these tips which will help you to enjoy the benefits and minimise the risks.

1. Plan your swim

Before you dive in, plan your day. Research the area of your swim, make sure it is safe, and you know different places to get in and out of the water safely. Check the type of ground - for lakes, canals, lough/lochs, are they rocky, flat, or slippery? For beaches, how do they shelve down? Be aware that many open water locations, such as remote coastal areas, rivers, and lough/lochs, may have steep or undercut banks or limited safe entry points and exit places 

Before entering the water, check the water temperature to ensure it is suitable for your level of experience and cold water exposure. Check current weather conditions and the forecast. Confirm that there is mobile phone coverage and make sure you have a waterproof cover for your phone. Also, consider factors relevant to your location, such as wind speed, currents, tidal flow or water flow, wave height, wind direction, and visibility. 

Plan your exit options before you get into the water. You should consider several exit points along your planned swim route just in case you need to stop your swim earlier than anticipated. 

Here are some key tips for planning your swim: 

  • Don’t swim alone.
  • Let friends and family know of your plans before swimming. 
  • Swim at a lifeguarded venue, beach, or accredited open-water swim venue, preferably (and especially if you are an inexperienced swimmer).
  • If you need help finding a venue, check out Beyond Swim, an accreditation programme for open water swimming venues. It’s managed by British Triathlon England and supported by Swim England and the Royal Life Saving Society UK (RLSS UK). If you are swimming in Ireland, we recommend getting in touch with Swim Ireland or looking at its open water programme.
  • Find other experienced swimmers in your area (e.g. through social media groups) and get advice on the best and safest places to dip and swim. 
  • When you arrive, take note of any warning signs. 
  • When at commercial venues, check they have adequate public liability and (where applicable) employers’ liability insurance. A well-run venue will be happy to provide certificates or will already have them on display.
  • Don’t forget sun and skin safety! Protect yourself with an effective, water-resistant sunscreen. Apply it 15-30 minutes before your swim so that it ‘sets’ and reapply it regularly according to the manufacturer's instructions or at least every 40-60 minutes.  

Additional notes for intermediate and advanced swimmers: 

  • If you swim where there are no lifeguards, do your own dynamic risk assessment so you fully understand the risks and have planned for them. Click here to find out more about risk assessments. 

2. Have the right equipment 

If you think all you need is a towel for open water swimming, this section is particularly important. Having the right equipment can save your life, so read on. 

Wear a buoyancy aid, such as a lifejacket, for activities on the water or at the water’s edge in case you fall in 

When you’re swimming at a supervised venue, follow their rules regarding safety equipment. These may include using a tow float, wearing a high-visibility hat or swimming in a wetsuit. Check before you arrive to ensure you have all the right equipment or that you can hire it at the venue. Some venues rely on this guidance as part of their insurance policy, so it is critical you follow their instructions.  

We recommend investing in a properly fitting wetsuit. Swimming with a wetsuit in open water is generally safer, especially in water around 18°C or lower, as it helps you retain warmth and improve your buoyancy. A swimming-specific wetsuit has the best flexibility, buoyancy, and warmth.  

Here's a general guide to the thickness of the wetsuit you should consider based on the temperature of the water you intend to swim in: 

  • Above 20°C: You typically may not need a wetsuit or can go with a thin one, around 1-2mm.UK & Irish coastal waters do not often exceed 20°C, but lakes and rivers may do in hot weather. 
  • 16-20°C: 2mm or 3mm wetsuit 
  • 14-17°C: 3mm or 4mm wetsuit  
  • 11-14°C: 4mm or 5mm wetsuit 
  • Below 12°C: 5mm or even a thicker wetsuit 

Your choice of wetsuit thickness depends on your comfort level, swimming ability, and the conditions you'll swim in. Choose a properly fitting wetsuit that is tight enough to keep you warm (reducing water ‘flushing’ beneath the suit) but doesn’t restrict your movement too much. You can also use equipment, including neoprene gloves, booties, a cap, and a hood, to reduce the impact of cold water. 

Our key wetsuit tips: 

  • We don’t recommend beginners swim in water of less than 12°C. You can still experience cold water shock and hypothermia in a wetsuit. Find out more about cold water shock 
  • Choosing the right wetsuit is down to personal preference. Some people feel the cold more than others, so you should consider your own tolerance for cold water when choosing a wetsuit thickness. Spend some time trying on different makes and types to find your ideal close-fitting suit.  
  • Bear in mind that a thicker wetsuit could mean restrictive mobility alongside increased buoyancy, and this could hinder some forward propulsion and body position while swimming. 
  • Some organisations recommend not wearing a wetsuit when the water temperature is over 22°C. At around 26°C, the temperature will be like that of a heated pool. Swimming in a wetsuit in these temperatures is not advised due to the risk of overheating. If you find yourself swimming in these water temperatures, make sure you drink frequently during and after your swim to prevent dehydration. 

Next, we recommend you wear a brightly coloured swimming hat. Research shows that fluorescent yellow or green, followed by fluorescent orange, are the most visible colours in water. Wearing a swimming hat also helps you retain warmth and can make your swim more comfortable. Silicon hats are slightly thicker and generally more robust than latex hats.  

In general, we recommend the use of a securely attached tow float or a similar device (e.g., a tow woggle or a dry bag) so that other water users can see you. It may also assist you in floating in an emergency. However, unless it’s been specifically tested for this use and you are following the exact manufacturer's instructions, we don’t recommend you rely on it as a lifesaving flotation device.  

Other equipment you may consider for keeping yourself seen and safe includes a whistle, a light, and neoprene gloves and footwear. If you anticipate rough terrain or colder water temperatures, you can wear water shoes or neoprene boots for added protection and comfort. We also recommend goggles, as they help with visibility and protect your eyes from hazards, including UV sunlight. One piece of equipment that is often overlooked is earplugs, which can prevent ear infections or conditions like surfer's ear (exostosis), where bone growth in the ear canal can occur due to repeated exposure to cold water. Earplugs can also help swimmers who suffer from dizziness, nausea, or vertigo. 

After your swim, you will need a towel and warm, dry clothes (multiple layers are good) ready to put on immediately—you can get chilled even on warm days. Some open-water swimmers use changing robes, which are convenient but not essential. You should also consider a hat, gloves, and a scarf. 

Take something to refuel, such as a sugary warm drink, soup, and a snack. A warm drink doesn’t help your body rewarm much, but it does make you feel more comfortable and replenish your fluids. 

Our key equipment tips:  

  • Write an emergency contact name and telephone number on your tow float with a permanent marker.
  • Prepare your clothes, drinks, or snacks before you enter the water. 
Additional notes for intermediate and advanced swimmers: 
  • Consider a buoyancy aid or lifejacket when you are travelling on foot, paddleboard, pack raft, etc., to remote or difficult-to-access areas where there is a greater risk of accidentally falling in. 
  • If you choose not to wear a wetsuit, remember that small changes in water temperature and ambient conditions can impact how long you can safely stay in the water. Your judgement can also be impaired if you get cold. Stay well within your limits. Understanding how your body reacts to cold water over time will help you stay safe while swimming. 
  • Winter swimming without a wetsuit is becoming more popular, with swimmers often just wearing wetsuit boots, gloves, and a warm hat. If you are doing this, keep the swim short and look for other cold-water swimmers to swim with. Even if you are experienced in cold open water swimming, our advice is not to do it alone and not to overdo it. If you are a regular cold water swimmer, you may become comfortable in cold water and will have little idea of the thermal profile of your body; don’t rely on how you feel to determine the duration of your immersion. 
  • We recommend using a tow float if you are swimming without a wetsuit, but there are some scenarios where using a tow float is awkward, such as in high winds, rough water, or swimming downstream in a river. You may also consider it unnecessary in places with no other water users. Consider whether a different emergency floatation device (such as a Restube) might be useful in these circumstances. 
  • Always use a tow float when other watercraft or boats are in the water. You should consider this even in a designated lake venue where there is no requirement for a tow float when wearing a wetsuit. 
  • Your choice of swim hat is up to you, but we recommend opting for a brightly coloured swim hat to enhance your safety and make you more noticeable to others in the water.  

3. Take a buddy with you 

Remember we don’t recommend you swim alone but that you go with a friend or an open water swimming group. It’s not only that they may have additional local knowledge and can help in an emergency, but it’s also more fun!  

We recommend that at least one of you has basic first aid knowledge—and ideally, open water first aid knowledge. Take some small items such as waterproof plasters or a small dressing, or swim at a venue that provides this equipment. Again, do not be afraid to ask, as a well-run venue will provide all this equipment as standard. 

Tell someone else where you are going—being as specific as possible—and when you expect to be back. 

Another key buddy tip: 

  • Once you are clear of the water, get dressed, and warm up, consider leaving a message for your' home' contact. 

Additional notes for intermediate and advanced swimmers: 

  • Think about gaining an open water safety qualification so you can keep yourself and your friends safer. 
  • Many beaches have poor phone coverage, so knowing where to go to pick up a signal could be critical if you are alone.  

4. Know your limits 

Acclimatising to cold water is an important step in enjoying a safe swim. Developed with Professor Greg Whyte, the former Olympian, world-renowned sports scientist, and physical activity expert, we have produced a Cold Water Exposure 2-week Home Plan Sponge to Plunge as a safe way to reduce the impact of cold water immersion.   

Ideally, you should start your swimming journey under the supervision of lifeguards or in a group setting.  

Choosing the right venue for your open-water swimming is important. For example, Scotland only has a few beaches with lifeguards, and not all lochs are suitable for beginners as they can be deep, cold, and have strong currents or undertows. Some may be too remote for safe access for the emergency services or may have unique features that reduce your accessibility and enjoyment. Do your research on the local area and choose somewhere that is known to be safe for swimming. 

Our key tips for swimming within your limits: 

  • Swim parallel to the shoreline wherever possible, stay at a depth that allows you to stand up, and keep away from deeper water, which will be colder. 
  • Plan and be aware of your exit point options, including those available in an emergency.
  • Avoid drifting in the currents by being aware of them before you enter the water.  
  • Keep an eye on a fixed landmark to ensure you’re not being carried by currents. 
  • Be aware of the direction of the wind, hidden and underwater obstacles, and bridges or breakwaters. 
  • Learn how to spot a rip current

Additional notes for intermediate and advanced swimmers: 

  • Unless you are a competent open water swimmer and are used to swimming in a particular environment, you should swim under the supervision of lifeguards. 
  • Even if you are accustomed to swimming in cold water, you could still face the risk of physical incapacitation if you remain in the water too long. This can happen within just 10 minutes of swimming in extremely cold water.
  • Wearing a wetsuit will increase the time you can safely swim, but the best advice is to learn your limits for cold water tolerance and stop swimming long before you reach them. 

5. How to stay safe and get help 

As part of your planning, consider the distance you might be from emergency support and the time it may take to arrive. Also, double-check that your phone is in a waterproof case and that you have a signal. 

If you get into trouble or feel overwhelmed in the water, ‘Float to Live’: 

  1. Fight your instinct to thrash around. 
  2. Turn on your back.
  3. Lean back.
  4. Get your breathing back under control. 
  5. Now, think about getting out. 

Familiarise yourself with any rescue measures in place where you are swimming, such as emergency signage and the location of the lifeguards or identify where the public rescue equipment is stored. 

Minimise your risk of infection by following these tips:  

  • Cover cuts and abrasions, however minor, with sticking plasters. Don’t swim if you have deep cuts. If you cut yourself while swimming, leave the water as soon as possible. Rinse the cut with clean water or a clean saline solution. Carefully remove any visible foreign objects, apply an antiseptic solution if you have one, and apply gentle pressure with a clean cloth or bandage. For all but minor cuts, we recommend calling 999/112.
  • In all cases, you should monitor the wound for signs of infection and seek further medical attention if you notice any. After swimming, always wash your hands in clean water or use an antibacterial gel before eating. 
  • Take a full shower at the earliest opportunity and thoroughly clean any cuts or grazes. Follow this up with an antibiotic cream to prevent infection. 
  • Try not to ingest water while swimming. 
  • Wash all your swimming kit (wetsuit, costume, goggles, hat, etc.) in clean water and thoroughly dry it before your next swim. 

There is always the possibility of getting injured or bitten by wildlife when you are open water swimming. Here is some basic advice on dealing with the most common occurrences: 

  • Stings from bees, wasps and hornets are usually more painful and alarming than dangerous, although some people are allergic to the poison, and multiple stings from a swarm of insects can be extremely dangerous. Likewise, stings in the mouth and throat can cause swelling, leading to suffocation. Apply a clean cloth soaked in cold water to relieve pain and swelling for up to 20 minutes. For stings in the mouth, if available, you should suck ice for immediate relief and call 999/112.
  • If you find a tick, remove it using tweezers or a tick remover by gently pulling the head upwards, using even pressure. Ensure you remove the head of the tick to prevent further infection. Place it in a sealed plastic bag and seek medical advice, taking the tick with you for analysis.  
  • If a leech bites you, don’t flick or pull it from the skin; it will fall off once it’s full of blood. Once it’s off, wash the wound and apply a clean cloth soaked in cold water for up to 20 minutes to relieve any pain and swelling. 
  • If you get stung by something like a jellyfish or Weever fish, notify a lifeguard or, for severe cases, call 999/112. Be aware that these stings can cause an allergic reaction and will need emergency help. Treat by rinsing the affected area with seawater (not fresh water), carefully remove any spines from the skin using tweezers or the edge of a bank card, then soak the area in very warm water (as hot as can be tolerated) for at least 30 minutes – use hot flannels or towels if you cant soak it. 
  • Snake bites are extremely rare, as only three types of snakes are found in the wild in the UK. The adder is the only common venomous snake. You should get all snake bites checked by a medical expert as soon as possible. Try to remember the colour and pattern of the snake to tell the doctor. 

    Our key tips for general safety: 

    • Download the GoodSam app, which has a growing database of the location of safety equipment, including water rescue equipment. You can also help protect fellow open water swimmers by uploading new locations of any emergency kit. 
    • To help get a better understanding of basic self-survival and rescue, take our free online water safety toolkit.

    Additional notes for intermediate and advanced swimmers: 

    • Take time to plan where you might end up and the distances you could be from emergency support during your swim. Consider the extra time it may take to arrive. This is particularly important when considering swimming in more remote areas. Considering emergency access before you swim could be critical.  

    6. Recognise when you’re too cold 

    Pay attention to your body’s reaction to cold water. If you start to encounter any of the following signs and symptoms, it’s time to get out and warm up. Some symptoms may even require you to seek medical attention.  

    Key signs and symptoms to look out for are:  

    • Shivering. 
    • Numbness or tingling.
    • While swimming, becoming upright in the water and getting slower.
    • Stiff limbs. Weakness or difficulty moving. Local cooling from cold water can make it difficult to move your arms and legs. 
    • Confusion or disorientation.
    • Blue lips or skin.
    • Feeling unusually tired or weak.
    • Rapid breathing and/or a high heart rate.
    • Uncontrolled clenched jaw.  
    • Difficulty in speaking. 

    If you experience any of these or see them in someone you are swimming with, find a safe exit, get yourself or them out of the water immediately, and warm up. 

    Our advice is to limit your exposure by time (e.g. less than 10 minutes if just in a swimming costume in cold water) and to get out of the water before you encounter any of the signs and symptoms, either in isolation or combined. If you are new to exercise or returning after a long break, it’s worth getting a medical check-up and advising your GP that you plan to take up cold open water swimming - for some medical conditions, cold water immersion is harmful.  

    Be aware of the ‘afterdrop’, a drop in your core body temperature post-swim. This results from continued cooling after you have left the water due to the cooling established while you were in it or insufficient insulation once you are out of the water. To minimise the afterdrop, quickly dry off and get into warm, windproof, and waterproof clothing and headgear as soon as possible. A warm water bottle in your towel or clothes can provide localised warmth, but avoid allowing direct contact with your skin, as it is easy to burn yourself when you have numb skin. Moving around generates metabolic heat; initially, it can increase cooling as cold muscles receive blood flow, but it is beneficial overall. If you have been in the water for less than 10 minutes, a warm shower or bath is okay for rewarming, but avoid very hot water and don’t stay in for long. After your shower, dry yourself completely and put on some warm clothes immediately. 

    Our key ‘too cold’ tips: 

    • Some signs and symptoms may not be related to your body’s reaction to cold water. For instance, an increased heart rate may simply be the result of exercise. Our advice is to be aware of all the signs and symptoms on the list and notice if you are experiencing several of them at the same time.
    • Be aware that if you are hypothermic (your body temperature is too low), you can paradoxically start feeling warm while still in the water. This is a major danger sign, and you should signal for help. 

    7. Know how to help someone in the water and in difficulty. 

    Open swimmers look out for each other. If you see someone in trouble, shout reassurance to them and tell them to float on their back (see ‘Float to Live’). Shout for help and ensure the emergency services are on their way - call 999 or 112 and ask for the Fire Service if you are inland or the Coastguard if you are on the coast. See if you can find a piece of rescue equipment if nothing is available, and without endangering yourself, reach out to them. Extend your reach with a stick, pole, or item of clothing and lie down or stay secure to the land. Alternatively, throw something buoyant to them, such as a part-filled plastic container, ball, or anything that will float. 

    Our key tips for helping others in trouble 

    • Local rescue equipment may often be next to a board with a location number, ‘what3words’ locator, and emergency contact numbers. 
    • Keep your eye on the swimmer all the time and shout reassurance, urging them to float on their backs if they are exhausted/very cold or to propel themselves to safety. 
    • Do not enter the water yourself. 

    8. Know when not to go! 

    However much you love open water swimming, sometimes you must accept it’s just not safe to go. Swimming during storms, heavy rain, thunderstorms, or strong winds can be dangerous due to the increased risk of lightning strikes, strong currents, and rough water conditions. If you go swimming soon after a storm, you may encounter large objects not commonly in the water, and possibly polluted waters. 

    Our key pollution tips: 

    • Pollution is an issue in all parts of the UK. To help you decide where to swim, download the Safer Seas & Rivers Service app, which our partners at Surfers Against Sewage have created. The app monitors water quality at 370 locations. You can also visit the Rivers Trust sewage map, which provides the best indication of whether you are in an area at risk of raw sewage overspills. 
    • Heavy rain can cause storm drains to overflow and discharge untreated sewage into watercourses. Land, road, and transport runoff can also result in chemicals or agricultural waste washing into the waterways.
    • Be cautious if you see blue-green algae blooms. Not all are toxic, but you cannot tell if a bloom is toxic by looking at it. If you see an algae bloom, it is best to assume it is harmful and not swim in the water. Avoid swallowing water if you are already in the water and swimming into blue-green algae. 
    • Trust your instincts regarding smell, water colouration, algae blooms, and what you can see floating in the water. If anything looks or smells wrong, it’s probably time to cancel your swim or go elsewhere. 
    • Keep your mouth closed and avoid swallowing if you are already in the water. If you are swimming to your exit point, swim with your face clear of the water.  
    • Observe and abide by any warning notices positioned around the water. 

      Natural hazards include pathogenic micro-organisms (bacteria and viruses), parasites, and toxic algae. Symptoms and illnesses from these hazards may include: 

      • Flu-like symptoms. 
      • Stomach and intestinal pain. 
      • Skin, ear, nose, and throat infections. 
      • Diarrhoea, fever, and vomiting. 
      • Chemical poisoning. 
      • Respiratory infections. 
      • Blood poisoning (septicaemia). 
      • Weil’s disease (leptospirosis). 

      It is always advisable to seek medical advice if you encounter any of these symptoms after open water swimming.  

      Here are some other circumstances when you should consider not swimming: 

      • If you're feeling unwell. 
      • When strong currents are present. 
      • After consuming alcohol or drugs. 
      • Near weirs or locks. 
      • At the mouth of an estuary. 
      • When there is no way of calling for help. 
      • If you require permission but don’t have it. 

      And finally… 

      Open water swimming, done safely, can be exhilarating but always prioritise safety and exercise caution when considering open water swimming, especially in unfamiliar or challenging conditions. Every time you swim, assess the risks and make informed decisions to ensure you have a safe and enjoyable swimming experience. This is a guide and cant cover every aspect of the unique nature of open water swimming, but we have designed it to help you learn and understand key safety messages, the impact of the environment, and your body’s reaction to cold water swimming. 

      Additional notes for intermediate and advanced swimmers: 

      As an intermediate or advanced swimmer, you should have the experience, knowledge, and understanding to make your swim as safe as possible. You should be familiar with a dynamic risk assessment; this is critical and will help you actively consider all the safety elements of your swim. Despite your skills, never forget the basics of good safety management, as this will help you get the most enjoyment from open water swimming. Remember, with cold water swimming, longer is not better; over time, the benefits diminish, and the risks increase significantly.  

      Above all, remember to Enjoy Water Safely! 


      RLSS UK would like to extend our sincere gratitude to the following individuals for their invaluable contributions to this guidance: 

      • Colin Hill
      • Helen Webster
      • Professor Greg Whyte
      • Professor Mike Tipton - Extreme Environments Laboratory, University of Portsmouth
      • Richard Timms
      • Robert Hamilton
      • Simon Griffiths  Outdoor Swimmer Magazine