TechRadar Verdict
The H2O Audio Sonar 2 Pro does a lot for the pool. Its form factor is very limited, but ideal for use with goggles or a headband while swimming. The integrated MP3 player as well as the Playlist+ function bypass the annoying problem of Bluetooth in the water. Unfortunately, low frequencies cannot be adjusted.
Benefits
- +
Ideal for serious swimmers
- +
Very stable
- +
Surprisingly clear underwater
- +
Playlist+ is an interesting and unique feature
Disadvantages
- –
The form factor is very limiting
- –
It only sounds good underwater
- –
Bass-rich sound
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H2O Audio Sonar 2 Pro: Review in two minutes
The H2O Audio Sonar 2 Pro is probably the best possible headset for serious swimmers. They attach to a headband instead of having their own (and are very stable once in place), which makes them unique among H2O Audio’s offerings and sets them apart from the rest of our best swimming headphones. Since Bluetooth connectivity is problematic in the water, H2O has added a few features to get around this problem.
As good as the H2O Audio Sonar 2 Pro are for swimmers, they’re probably among the least interesting headphones for anything else. They only sound good underwater – that’s by design, of course – and it’s still not quite an audiophile experience. And this form factor is very limiting. While some of our best running headphones use bone conduction technology and can be used in water and on land, there are other options, even from H2O Audio, that I prefer for this purpose, like the H20 Audio Tri 2 Pro, ranked among our best bone conduction headphones overall.
But for their intended use, you’ll be hard-pressed to do better than the H2O Audio Sonar 2 Pro. With that in mind, let’s dig a little deeper into why.
Although I already had an idea of what to expect when I received these earbuds, I was surprised by the small size of the box – it’s not much bigger than the box the AirPods come in – nor the small size of the soft case inside, which was basically the same size as the box.
The earbuds themselves came inside the case with the charging cable folded and a pair of waterproof earplugs. The headphones themselves, aside from being quite small, have a unique look because they don’t have a headband of their own, just a thick blue cable that runs behind the head and connects the speakers to each other.
The bone conduction drivers are each in a black housing with a clip on the outside and three control buttons – the left one has mode (toggles between Bluetooth mode and using internal storage in memory mode), forward and reverse, while the right one has Play/Pause/Power and Volume Up/Down.
Since they’re designed for swimming, they have an IPX8 rating – about as good as any consumer product not intended for the Mariana Trench – and therefore can be underwater “up to 12ft/3.6m” without any restrictions. If you plan to use them for serious diving, be aware that pressure in deeper waters could affect these headphones.
Additionally, since the H2O Audio Sonar 2 Pro is designed for swimming, it comes with a few features intended to get around one of the biggest obstacles to using headphones while swimming. Bluetooth connectivity tends to become more and more intermittent the more water there is between the source like a smartphone and headphones, so these headphones come with a built-in MP3 player with 8GB of storage.
Loading music on these headphones is then reminiscent of loading music on a phone as one could have done ten years ago, which is not the most practical, by using the charging cable provided and connecting the headphones to a computer. This also means that you need to store the music you want in a playable form like MP3 on your computer.
The H2O Audio Sonar 2 Pro has one additional feature to make this more manageable that the non-Pro version doesn’t have, and that’s the Playlist+ feature. This feature allows the user to load music onto the wireless earbuds. Now, H2O Audio advertises this feature as a way to transfer a playlist, but that overcomplicates what this feature actually does.
Think of the Playlist+ feature like a tape recorder. Whether you do it through the headphones (you press the volume up button twice to start and stop recording) or through the app, you essentially start the recording process, press play on the music or podcast of your choice, then stop it when the song is finished. This won’t stop on its own, so you could potentially have multiple songs on a single track. One thing I like is that it will read the song name and title from the source and automatically name the file after it. This is a good workaround, if a bit inelegant. It’s literally a digital version of pressing “record” on a boombox to create a mixtape.
Whether you’re streaming via Bluetooth or listening to an MP3 in memory mode (i.e. the built-in MP3 player), the sound quality is the same. And it’s a bit strange. How bone conduction headphones work affects sound quality a bit, since what you’re listening to vibrates through your cheekbones to your inner ear instead of actually going through your ear. So everything sounds more intelligible when you also wear the included earplugs.
The sound is also clearer underwater. The listening experience is not quite hi-fi, however. I’ve listened to H2O Audio products underwater before and I don’t remember them being this bass rich. Perhaps it’s intentional to make the music more uplifting, but the bass seems to be front and center to the point where a song like “In-A-Gadda-Da-Vida” sounds like a bass solo and songs with 808 drums like hip-hop and EDM are somewhat overpowered by the kick drum.
The weird thing is that there’s no real way to EQ the headphones in a way that compensates for it, especially if you’re using memory mode (you can always use an EQ on the phone for Bluetooth audio). That said, the mids and highs are quite clear underwater, so if H2O Audio adjusted their app to have some sort of EQ setting, I think these headphones would be even easier to recommend.
They remain easy to recommend, despite this problem with the low end. I haven’t really discussed fit yet, and while you’re somewhat at the mercy of which headband you use, when they’re on, they’re incredibly stable. They don’t move. They don’t move. I learned by wrestling or swimming my way through a few laps in an Olympic-sized pool to see what would happen. This is one of the main reasons why they are some of the best swimming headphones.
There’s nothing else to say about the H20 companion app other than mentioning that it will give you a battery life readout and allow you to browse songs stored on the device in memory mode. You can also start the Playlist+ functionality here.
Finally, the 10-hour battery life doesn’t seem impressive compared to what we see on the best wireless earbuds, especially when you include the extra charges in their carrying case – something you don’t get with the soft case since it’s not a power source. But I think it’s actually a good amount of juice for a swimmer.
H20 Audio Sonar 2 Pro: Specifications
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|
Component |
H20 2 Pro audio fishfinder |
|
Drivers |
Bone conduction |
|
Active noise cancellation |
No |
|
Battery life |
Until 9 a.m. |
|
Weight |
1.0 ounce (29 grams) |
|
Connectivity |
Bluetooth5.3 |
|
Frequency range |
30Hz – 18kHz |
|
Waterproofing |
IPX8 |
|
Other features |
8 GB storage and MP3 player, Playlist+, app support |
H2O Audio Sonar 2 Pro: Price and availability
- How much does it cost? $149.99 / £117.00 / AU$234.00
- When is it available? Available now
- Where can you get it? Available in the US, UK and Australia
The H2O Audio Sonar 2 Pro aren’t cheap, but the price is very respectable at $149.99 / £117.00 / AU$234.00. Given the feature set and niche usage, I could see a higher price (although I hope H2O Audio gives more control over the EQ before that happens).
Most swimming headphones and bone conduction headphones end up costing at least the same, if not more. The Shokz OpenSwim Pro, for example, costs a slightly higher $179.95 / £169 / AU$299. They also have a built-in MP3 player, but have nothing like the Playlist+ functionality (which is a proprietary feature of H2O). They also have the more typical form factor of a pair of bone conduction headphones with a sturdy but foldable headband.
Even the company’s H2O Audio Tri 2 Pro Multi-Sport has a higher MSRP of $199.99 / £155.68 (around AU$310). Of course, these are intended for a different purpose. They’re sturdy and stable enough to swim in, but won’t snag, as they’re just as much intended for running. They also have the Playlist+ function.
- Value rating: 4/5
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|
Attributes |
Remarks |
Rating |
|---|---|---|
|
Value |
The price of these headphones is quite reasonable, as one could definitely pay more for swimming headphones. |
4/5 |
|
Design |
Although a niche design, the H2O Audio Sonar 2 Pro are ideal for swimmers thanks to their safety. |
4.5/5 |
|
Performance |
The sound quality, while a little bass-heavy, is clear underwater. Additionally, the battery life is more than sufficient. |
4/5 |
|
Average rating |
It may be niche, but swimmers who need clip-on headphones will be happy with this. |
4/5 |
Should I buy the H2O Audio Sonar 2 Pro?
Buy it if…
- Tested over a few weeks
- I listened to different genres of music
- Tested all the different features
I spent a few weeks testing the H2O Audio Sonar 2 Pro, including a few laps in an Olympic-sized pool and simply spending time underwater listening to them. Using them, I listened to all kinds of genres, from electronic and hip-hop to rock and acoustic music, to get a feel for their sound. I also tested the different features, including the Playlist+ feature.
After testing, it’s clear that they are ideal for serious swimmers, not only because of the bone conduction but also the form factor, meaning they are as secure as a pair of headphones can be during a swim. Check out our guide to how bone conduction headphones work for more details on how such headphones work.
I’ve spent the last few years reviewing audio equipment and have spent even more time using my critical ear as a listener and musician to understand what sounds good and what doesn’t.
- First review in November 2025
James Holland loves checking out gadgets of all kinds, from audio equipment to laptops to vacuum cleaners (especially the robot type), and has done so for a number of future publications including TechRadar, Top Ten Reviews, Homes & Gardens and T3. He has acquired expertise in in-depth examination over the past four years. When he’s not working on the latest technology, he loves traveling, playing music, and eating questionable foods.