I spent 2 weeks testing the H2O Audio Sonar 2 Pro, and found them to be the perfect headphones for swimming

H2O Audio Sonar 2 Pro: Two-minute review

The H2O Audio Sonar 2 Pro are possibly the best possible headphones for serious swimmers. They secure onto a headband instead of having their own (and are very stable when in place), making them unique among H2O Audio’s offerings as well as setting them apart from the rest of our best swimming headphones. Since Bluetooth connectivity has trouble in water, H2O has added some features to get around that.

As good as the H2O Audio Sonar 2 Pro are for swimmers, they’re probably among the least interesting headphones for any other purpose. They only sound good underwater – this is by design, of course – and it’s still not quite an audiophile experience. And that form factor is very limiting. While some of our best running headphones list 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 that purpose, such as the H20 Audio Tri 2 Pro, rated our best bone conduction headphones overall.

But for their intended purpose, you’ll be hard-pressed to do better than the H2O Audio Sonar 2 Pro. With that in mind, let’s dive a little deeper on why that is.

While I already had an idea of what to expect when I received these headphones, I was surprised by how small the box was – it’s not much bigger than the box AirPods come in – nor how small the soft-shell case inside was, which was basically the same size as the box.

The actual headphones came inside the case along with the folded up charging cable and a pair of waterproof earplugs. The headphones themselves, besides being fairly small, are unique looking because they have no headband of their own, just a thick, blue cable that goes behind one’s head connecting the drivers to each other.

The bone conduction drivers are each in black housing with a clip on the outside and three control buttons – the left has the Mode (switches between Bluetooth Mode and using internal storage in Memory Mode), forward and back, while the right has Play / Pause / Power, and Volume Up / Down.

Since these are made for swimming, they have an IPX8 rating – about as good as it gets in any consumer product not meant for the Mariana Trench – so it can be underwater “up to 12ft/3.6m” without any restriction. If you’re considering these for serious diving, be warned the pressure in deeper waters could affect these headphones.

Also, since the H2O Audio Sonar 2 Pro are made for swimming, they come with a couple features meant to circumvent one of the biggest hurdles for using headphones while swimming. Bluetooth connectivity tends to become more intermittent the more water is between the source like a smart phone and headphones, so these headphones come with a built-in MP3 player with 8GB of storage.

Loading music onto these headphones then is reminiscent of loading music onto a phone as one might have done ten years ago, which is not the most convenient, using the included charging cable and connecting the headphones to a computer. That also means that you have to have the music you want stored in playable form like MP3 on your computer.

The H2O Audio Sonar 2 Pro do have an additional feature to make this more manageable that the non-Pro version doesn’t have, and that’s the Playlist+ feature. This feature lets the user load music onto the headphones wirelessly. 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 the app, you basically start the recording process, press play on whatever music or podcast you want, and then stop it when the song is done. It won’t stop on its own, so you could potentially have multiple songs on one track. One thing that I do appreciate is that it will read the name and song title from the source and automatically name the file after it. It’s a nice work-around, if a little inelegant. It’s literally a digital version of pressing ‘record’ on a boombox to make a mixtape.

Regardless of whether you’re streaming through Bluetooth or listening to an MP3 in Memory Mode (aka the built-in MP3 player), the sound quality is the same. And it’s a bit strange. The way bone conduction headphones work affects the sound quality a little, since what you’re listening to is vibrating through your cheekbones into the inner ear instead of actually passing through your ear. So, everything sounds more intelligible when also wearing the included earplugs.

It also sounds clearer when underwater. The listening experience is not quite HiFi, however. I’ve listened to H2O Audio products underwater before and I don’t remember them being as bass-heavy. Maybe it’s intentional to make the music sound more motivating but the low-end 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.

What’s strange is that there’s no real way to EQ the headphones in a way to offset 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 fairly clear when underwater, so if H2O Audio adjusted their app to have some kind of EQ adjustments, I think these headphones would be even easier to recommend.

They’re still easy to recommend, despite that issue with the low-end. I haven’t really discussed fit yet, and while you’re somewhat at the mercy of whatever headband you use, when these slip on they’re incredibly stable. They don’t move. They don’t jiggle. I learned by struggling or thrashing my way through a couple laps in an Olympic pool to see what would happen. This is a big reason why they’re among the best swimming headphones.

There’s not else to write home about regarding the H20 companion app, other than to mention that it will give you a readout of battery life and let you navigate the songs stored on the device when in memory mode. You can also start the Playlist+ feature here.

Lastly, 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 shell case as it’s not a power source. But I think it’s actually a decent amount of juice for a swimmer.

H20 Audio Sonar 2 Pro: Specifications

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. Considering the feature set and niche use, I could see a higher price (though I would hope H2O Audio would give more control over the EQ before that happens).

Many of the swimming headphones and bone conduction headphones end up going for at least the same price if not more. The Shokz OpenSwim Pro, for example, go for a slightly higher $179.95 / £169 / AU$299. They also have a built-in MP3 player but don’t have anything like the Playlist+ feature (which is a proprietary H2O feature). They also have the more typical form factor of a pair of bone conduction headphones with a sturdy but bendable headband.

Even the company’s own H2O Audio Tri 2 Pro Multi-Sport has a higher MSRP $199.99 / £155.68 (about AU$310). Of course, those are meant for a different purpose. They are sturdy and steady enough to swim in, but don’t clip in, as they’re meant just as much to run in. They do come with the Playlist+ feature as well.

• Value score: 4 / 5

Should I buy the H2O Audio Sonar 2 Pro?

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How I tested

• Tested over a couple weeks
• Listened to different genres of music
• Tested all the different features

I spent a couple of weeks testing the H2O Audio Sonar 2 Pro including a couple laps in an Olympic size pool as well as just hanging out underwater to listen to them. While using them, I listened to all sorts of genres from electronic and hip-hop to rock and acoustic music to get an idea of how they sound. I also tested the various features, most notably the Playlist+ feature.

After testing, it’s clear that these are ideal for serious swimmers, not only from the bone conduction but the form factor, which means that they’re 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 headphones like these work.

I’ve spent the last few years reviewing audio equipment and have spent even longer using my critical ear as a listener and musician to understand what does and doesn’t sound good.

• First reviewed November 2025