How to Start Open-Water Swimming: 6 Things That Change When You Leave the Pool for the Sea

Advenway 16 September 2026 updated 20 October 2026 Share f W X P @

A swimmer doing front crawl in choppy open water

You might swim regularly in a pool, feel comfortable with your breathing and cover a few hundred metres without stopping. Then you get into the sea, and within the first 50 metres you’re thinking, “I know how to swim. Why does this suddenly feel so difficult?” Don’t worry. You haven’t forgotten how to swim. Open-water swimming is more than taking your pool session outdoors. There are no lane markings or walls, and the water isn’t always calm. Visibility can be limited, you have to find your own way, and even a small wave can interrupt your breathing rhythm.

That’s why your first goal should be getting to know the new environment, rather than covering a long distance. Feeling comfortable in open water develops through experience, calmness and good judgement, alongside fitness. So, what actually changes?

1. There’s No Lane Line to Follow

In a pool, you don’t have to think much about navigation. You follow the line on the bottom, see the lane ropes beside you and know when you’re approaching the wall. In the sea, it’s quite normal to drift left or right after a few strokes. Often, you won’t even notice. When you look up, you may discover you’re heading somewhere quite different from your original target.

One of the first skills to learn is therefore sighting. This means briefly lifting your eyes above the surface to check a fixed landmark on shore. It could be a building, a jetty, a large tree or another distinctive feature. Something visible from a distance is easier to use than a small object that’s hard to pick out.

To begin with, you can try sighting every 6–10 strokes. But lifting your head too high makes your hips and legs drop, slowing you down. You’re aiming for a quick glimpse of your landmark, followed by a return to your normal swimming position, rather than a long look around. For your first attempts, swimming parallel to shore between two nearby landmarks makes things much easier.

2. The Water Doesn’t Stay Still

Pool water doesn’t have a personal plan for you. The sea sometimes feels as though it does. Waves, wind and currents directly affect your swim. You might move comfortably in one direction, only to find the same distance much harder on the return. Your fitness hasn’t disappeared in a few minutes. The conditions are different.

Currents that carry you away from shore deserve particular attention. Trying to fight a strong current head-on can tire you out quickly. Before entering, learn about local currents, boat traffic and any warnings for the area.

The best day to start isn’t the day the sea looks most dramatic. It’s a day when conditions are as calm as possible. If there’s strong wind, noticeable swell, fog that limits visibility or heavy boat traffic, postponing your swim isn’t a failure. Knowing when to stay out is part of open-water swimming too. Stay close to shore during your first swims. Swimming parallel to the beach means you have a shorter way out if you become tired or uncomfortable.

3. Waves Can Change Your Breathing Rhythm

In a pool, you largely choose when and on which side to breathe. In open water, a little wave may reach your face at exactly the moment you turn for a breath. That’s frustrating at first. After swallowing a little water, you may find yourself speeding up, breathing more frequently and starting to panic. Often, it’s the disrupted rhythm afterwards that causes the biggest difficulty.

Being able to breathe to either side is a real advantage. If waves keep coming from your right, breathing to the left may feel more comfortable. But if bilateral breathing isn’t familiar yet, practise it in the pool rather than trying to learn it at sea.

Don’t start swimming hard as soon as you enter the water. Spend a few minutes in the shallows, put your face in and settle your breathing. Swim the first 100 metres more slowly than your usual pool pace. If water gets into your mouth, try not to treat it as a crisis. Slow down. If needed, switch to breaststroke or roll onto your back to recover your breathing. Don’t try to speed up again before your breathing feels settled.

4. There’s No Wall Every 25 Metres

Pool turns create small breaks you may barely notice. You touch the wall, turn, push off and pick up speed again. None of that happens in open water. That’s why swimming 500 metres in a pool may feel different from swimming 500 metres continuously in the sea. You keep moving while also sighting, handling waves and maintaining your position.

You don’t need to match your longest pool distance on your first open-water outing. If you can swim 1,000 metres in a pool, that doesn’t mean your first goal should be to swim 1,000 metres away from shore. A controlled 10–15-minute swim close to land is far more useful. You can create your own little pause points:

Swim comfortably towards your chosen landmark.
Float briefly on your back and check your breathing.
Look around and assess your position.
Continue if you feel comfortable.

Being able to stop, stay afloat and start swimming again matters just as much as swimming continuously.

5. Water Temperature Makes More Difference Than You Think

The air can be warm while the sea is still cold. Especially early in the season, sunshine can give you the wrong impression of the water temperature. Entering cold water suddenly can cause rapid breathing, muscle stiffness and a feeling of panic. Rather than jumping off a jetty or swimming straight away, enter gradually and in control.

Let your feet and legs adjust first. Then wet your torso, gently put your face in a few times when you feel ready, and allow your breathing to settle. If you can’t control your breathing during those first minutes, don’t swim out. A swimming wetsuit can reduce heat loss in cold water and provide some extra buoyancy. But it isn’t armour that keeps you safe in every situation. Choose one designed for swimming that doesn’t restrict your shoulders.

Act promptly once you’re out, too. Remove wet kit, dry off and put on dry clothes. If shivering increases, your coordination deteriorates or you feel light-headed, don’t dismiss it as simply feeling a little chilly.

6. Your Mind Has More to Process

On your first open-water swim, not being able to see the bottom may feel unsettling. Seaweed might brush your foot. You may hear a boat in the distance or look towards shore and feel farther out than you expected. None of those things is about your swimming technique, but they can directly affect how you swim.

Overhead view of a person swimming in dark open water where the bottom isn't visible — Not being able to see beneath you can affect your breathing and rhythm, regardless of your technical ability.

As anxiety rises, breathing speeds up. Faster breathing disrupts your stroke rhythm. That makes you more tired, which can reinforce the feeling that something is wrong. The way to break that cycle is to build familiarity gradually, rather than push yourself hard on day one.

During your first sessions:

Spend a few minutes swimming where you can still stand.
Make short swims parallel to shore.
Stop periodically to check your surroundings.
Get out while you still feel comfortable.

Finishing your first swim completely exhausted doesn’t mean it was a better session. Getting out thinking, “I could have done a little more,” can help you return feeling more confident and keen to try again.

How Well Do You Need to Swim Before Starting?

It wouldn’t be helpful to set a strict distance requirement. How far you can swim in a pool doesn’t, on its own, tell you whether you’re ready for open water. Even so, these skills will make the transition much easier:

Swimming a few hundred metres at a comfortable pace.
Pausing in the water to recover your breathing.
Rolling onto your back and staying afloat.
Slowing down without panicking.
Controlling your breathing during basic front crawl.

If any of these feels difficult, spend some time with a swimming coach in a pool first. Open water isn’t the ideal place to learn basic swimming skills.

What Should You Bring for Your First Open-Water Swim?

You don’t need a huge kit bag to get started. A few items can make you more comfortable and easier to see:

Well-fitting swimming goggles.
A brightly coloured swim cap that’s visible from a distance.
A swim buoy to improve visibility.
A swimming wetsuit if the water temperature calls for one.
Sun protection.
Warm, dry clothes for afterwards.
Drinking water.

A swim buoy isn’t a life jacket. Its main purpose is to make you more visible and, where the design allows, provide something to hold briefly if needed. Using one doesn’t make swimming alone or in unsuitable conditions safe.

A Simple Plan for Your First Open-Water Swim

On day one, pay more attention to the experience than the distance.

Before entering: Check the weather, wind, waves and local boat traffic. Decide where you’ll get in and out.
The first 3–5 minutes: Stay in shallow water. Put your face in when comfortable and settle your breathing.
The next 5 minutes: Swim parallel to shore at a very relaxed pace. Sight regularly.
A quick check-in: Pause and ask yourself: Is my breathing calm? Am I getting cold? Can I get back to shore easily?
The final few minutes: If everything feels comfortable, swim a little longer and get out before you become tired.

This might feel like a small session. That’s fine. The aim is to discover how the sea feels, rather than set a training record.

Don’t Start Open-Water Swimming Alone

This is the most important part of the article, ahead of equipment or technique. For your first attempts, go with an experienced open-water swimmer, a swimming group or a coach where possible. Choose places where swimming is permitted, lifeguards are present and swimmers are separated from boat traffic. Stay close to the people you’re swimming with, and tell someone on land about your route.

Water safety organisations such as the RNLI and the Royal Life Saving Society also emphasise swimming with others, being visible, checking conditions beforehand and entering gradually. If you feel unwell, aren’t sure about the conditions or simply feel that something isn’t right, staying out is the sensible decision.

Get to Know the Sea

One of the lovely things about open-water swimming is that every session feels a little different. Water temperature, wind direction, visibility and waves change. Over time, you learn to adapt your swimming to those conditions. The pool helps build your technique and fitness. The sea teaches you to navigate, stay calm and read your surroundings. Start with short swims, stay close to shore and increase your distance gradually. Progress in open water is measured by how comfortably and calmly you can swim, rather than how far you venture from land.