The swim buoy is one of the first pieces of equipment we at Watery recommend when someone asks us about open water swimming.
Not because it's the coolest gadget.
But because it makes a real difference - for both your safety and your experience in the water.
This guide is for you if you're either considering buying your first swim buoy or if you've already got one and want to use it correctly.
We cover everything: what it can do, which model suits you, how to get it ready in under two minutes - and what to do if it starts losing air.
What is a swim buoy - and what can it do?
A swim buoy is an inflatable floating device that you attach to your waist with a strap.
It floats behind you in the water while you swim.
You hardly notice it - it doesn't slow you down and doesn't get in the way of your arm movements.
In the swimming community, three names are used for exactly the same product:
- Swim buoy - the most common Danish name
- Swim buoy - the English term that many search for
- Havtaske - a popular everyday name in Denmark, even though it's technically a fish 😂
The confusing part is that the product is actually two things at once:
A buoy that keeps you visible and afloat.
And a waterproof bag where you can store your belongings dry and safe.
Most models have a sealed compartment for your phone, keys, and snacks - and many also have a transparent touch window at the front, so you can see and operate your phone without opening the bag.
Why you swim safer with a swim buoy
A swim buoy is not just a smart gadget.
It's the one piece of equipment that makes the biggest difference for your safety when swimming in open water.
Here are the three reasons why we never jump into the water without one:
1. Visibility in the water
Open water is not a marked swimming lane. Here you share the water with kayaks, motorboats, and SUP boards - and they don't see you unless you make yourself visible.
A swim buoy in orange or green floats high behind you and catches attention from far away.
It's the most effective way to avoid an accident.
And honestly: it's the only reason you really need.
2. Your belongings with you on the trip
What do you do with your phone, keys, and wallet when swimming from the beach?
Leave them on the towel and hope for the best?
With a swim buoy, you have a waterproof compartment strapped to your waist.
Your belongings stay with you the whole trip - and they remain dry, even if the buoy gets hit by waves.
3. A resting place in the middle of the water
Even experienced swimmers may need a break.
Fatigue, cramps, or an unexpected current - it happens to everyone at some point.
A swim buoy doesn't support your weight and won't keep you afloat like a life jacket.
But you can lean on it and rest in the water while you catch your breath.
It's a small thing that can mean a lot far from shore.
How to choose the right swim buoy
There are differences in swim buoys - and the right choice depends on what you need it for.
Here we guide you through the most important decisions.
Size: 20L vs. 28L - what's the difference?
The size is about how much you want to bring into the water.
- 20 liters - fits keys, phone, and a small snack. Good for shorter trips where you want the least resistance in the water.
- 28 liters - offers more space: larger water bottles, extra clothes for changing on the beach, or just more air for better buoyancy as a resting tool.
Unsure which to choose? Then go with 28 liters. It's our best-selling size - and it's still light enough that you don't notice it in the water.
Swim buoy materials: PVC vs. TPU - what's the difference?
The two materials behave differently - both in the water and in the bag at home.
- PVC - robust and affordable. Withstands harsh weather and rough surfaces. Weighs a bit more and is harder to pack compactly.
- TPU - lighter, more flexible, and can be folded much smaller. Good for those who travel a lot or run to the start of a race.
For everyday use and most recreational swimmers, PVC is more than good enough.
TPU is worth considering if you compete or travel with your equipment.
Swim buoy for triathlon
Are you using the swim buoy for training towards a triathlon race? Then there are a few things to keep an eye on.
Many official triathlon events do not allow swim buoys during the race itself - always check the rules for your specific event.
For open water training, however, it's perfect: it makes you visible, so you can safely focus on technique and pace.
We recommend a model with a strap that fits securely around the waist without slipping - and preferably one in a color that's highly visible in low light and murky water.
Should you choose with or without a touch window for the phone
Many swim buoys have a transparent window at the front where you can slide your phone in and still see the screen - and even operate it with your finger.
It's handy if you use your phone for GPS tracking of the trip, listen to music along the way, or just want it easily accessible.
If you don't need any of these, it's a nice-to-have rather than a must-have.
What you can put in your swim buoy - and what to avoid
The swim buoy is waterproof - but that doesn't mean everything can come along.
Here's a quick overview of what works and what you should leave on land.
Things you can definitely bring:
- Mobile phone (preferably in an extra small ziplock bag for safety)
- Keys - without sharp edges that can damage the inside
- Wallet or cash in a small bag
- Energy gel or small snacks
- Small waterproof power bank
- Sunscreen in a sealed bag
Things to avoid:
- Sharp objects like knives, scissors, or keys with pointed edges - they can puncture the buoy from the inside
- Too heavy content - it increases resistance in the water unnecessarily
- Items that can leak, like open water bottles or creams without lids
- Larger electronics like tablets or big cameras
How to prepare the swim buoy for use - step by step
It takes less than two minutes. Here's how you do it.
1. What you get in the package
In the package, you'll find: 1 bladder, 1 short strap for the bag, and 1 belt with male/female buckle.
2. Attach the short strap
Attach the short strap around the handle of the swim buoy.
3. Thread the long strap through the short one
Thread the long strap of the belt through the short strap so the two are connected.
4. Pack your belongings in the buoy
Place your items in the waterproof compartment.
Roll the opening down to the mark on the back of the buoy - and click it shut.
5. Inflate from the back
Remove the protective cap over the valve at the back.
The first breath should be strong - it sets the valve in place.
Inflate until the buoy is completely firm.
6. Inflate from the front
Turn the buoy over and repeat in the front valve.
The air fills the space around the touch window at the front.
7. Ready - jump into the water
Fasten the belt around your waist and adjust for a comfortable fit.
The buoy floats behind you and follows your movements.
8. Deflate after use
When you're done using it, it needs to be deflated. Flip the small flap over the valve and press it against the valve.
The air escapes - and the buoy is ready to be folded and stored away.
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Care and storage after use
A swim buoy lasts for many years - if you treat it right.
- 3 - 5 days delivery, on weekdays.
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What to do if the swim buoy loses air?
Fortunately, it doesn't happen very often – but it does happen sometimes. Here's what you should do.
- Check the valve first. Most cases are due to a valve that isn't completely closed. Press the protective cap down well and inflate the buoy again. Does it hold air now? Then that was the solution.
- Check if the opening is rolled down correctly. If the waterproof compartment isn't rolled down far enough or isn't clicked shut properly, air can escape along the edge.
- Is there a hole in the material? Fill the buoy with air and hold it under water – look for bubbles. If you find a hole, it can be patched with PVC repair tape or neoprene glue for minor damage.
Hope you're more inclined to try out such a swim buoy now. It certainly doesn't get cheaper or easier to protect yourself from danger and theft.
What is a swim buoy? A swim buoy – also known as a swim buoy or sea bag – is an inflatable floating device that you attach around your waist with a leash and pull behind you while swimming. It enhances visibility in the water and typically includes a waterproof compartment for storing keys, phones, and other belongings. Does a swim buoy slow you down when swimming? No. A swim buoy floats on the water's surface behind you, following your movements. Most swimmers barely notice it. The lighter you pack it, the less resistance you'll experience. Is a swim buoy the same as a life jacket? No. A swim buoy is not a life-saving device and does not replace a life jacket. You can rest on it and use it for support, but it will not keep you afloat automatically. A life jacket is the only equipment that guarantees buoyancy. Does a swim buoy keep your belongings dry? Yes, when the opening is properly rolled down and clicked in place. The waterproof compartment is designed to keep water out, even in waves. For extra safety, you can place your phone in a ziplock bag first.
Former elite swimmer and founder of Watery.ie
Daniel has swum open water at an elite level and knows exactly what makes the difference between a safe and an unsafe trip in the sea. The swim buoy is one of the first pieces of equipment he recommends to anyone starting to swim outside the pool – and it's this experience he's based this guide on.
Read more about Daniel and Watery here