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?

Buy it if...

Don't buy it if...

Also consider

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

Zygo Z2: One minute review

The Zygo Z2 are part of a very small world of headphones, namely bone conduction models made for being used in the water. Yet even in this small space, they are unique. They’re not the only swimming headphones that you should consider, but they are the only ones that use a radio transmitter for listening to music in the water. There's no onboard MP3 player, so they're the only pair that you don’t need to sit down with in front of your computer, to manually load the headphones with music before heading to the pool.

And while that’s the big selling point you’ll see when you come across them on their website or on Amazon, the Z2s also offer a deep ecosystem within the downloadable app including a whole assortment of classes, along with features like a walkie talkie and lap counting, hidden behind an additional but low subscription fee. This makes the Zygo Z2 function like a Peloton for the pool. I’m not sure I’ve seen anything like that before.

Of course, they do come at a hefty price (and that’s before the aforementioned subscription fee), and the sound quality is not going to compete with the best wireless earbuds. But that’s to be expected with headphones that first, use bone conduction, and second, use radio transmission.

If you have a smartphone (and I’m going to assume you do), you might be aware that phones connect to devices via WiFi, data, and Bluetooth, not radio waves (even if you’re streaming a radio station through your phone, it’s coming to you digitally). Because of that little omission, the Zygo Z2 needs more than just a pair of headphones to function.

Enter the biggest headphones charging case I’ve ever seen in my life. This big black square measures a little under seven inches across and under three inches deep. There’s a flip lid hiding the headphones and earplugs, as well as the USB-C charging port, LED indicator, and the power / connectivity button. Most unique here though is the shark fin on the back that needs to be flipped up during use, like an antenna. Without it, there are no radio waves.

The headphones inside have an IPX8 rating, use bone conduction for sound, and come in the same imposing matte black as the charging case. On the back of the headphones, the volume up (also power) and down sit on either side of the Zygo logo.

Be aware when ordering the Zygo Z2 that they come in two sizes: Standard and Large. If you go by the size guide and choose wisely, you’ll end up with a snug fit. They never fell off, adjusted, or really moved at all. And despite their tight fit, I found them comfortable to wear.

I can get up to three hours’ of battery life during use, which is a bit lower than the competition (but likely to be more than enough for a single session), though using a completely different technology (the radio transmission) might have something to do with that. The charging case does at least have seven charges in it, so its overall battery life (when including the charging case) is about the same as other bone conduction headphones that have a charging case, and far more than those that don’t. For reference, many of the better bone conduction headphones last around nine to ten hours.

I feel obligated to share our "how do bone conduction headphones work?" article as this type of sound reproduction is such a niche within headphones. They’re really only popular when searching specifically for the best waterproof headphones or best running headphones, with a possible exception for office work. In essence, they sit on the bones in front of your ear, circumventing the outer ear, which make them great for use in the water.

It’s also why the Zygo Z2 (and most other swim-focused headphones) come with a pair of earplugs. They, like the charging case and headphones, come in a fetching Darth Vader black. They’re necessary for hearing the headphones, allowing you to focus on the audio vibrating through your cheek bones (It’s less weird than it sounds).

If you’re wondering how “Eye of the Tiger” gets from your phone to your ears, it starts with a smartphone using the Zygo app, which is then paired to the charging case (a simple Bluetooth pairing process) in turn automatically connected to the headphones via radio waves. The Zygo app showcases the full breadth of the Z2’s features. I can use the app to communicate with someone else wearing the headphones. It is one-way though, so the wearer can’t talk back (only really useful if you have a swimming coach).

To use this feature, you need to get the five-dollar-a-month subscription, which also includes lap counting and a large assortment of on-demand classes consisting of audio workout guidance. Having listened to a few, I found them easy to follow and understand as well as well-paced. I think this ecosystem of classes are also what separates the Zygo Z2 from other swimming headphones.

Unfortunately, the audio quality leaves a bit to be desired. Now it’s not bad and having the audio coming through radio waves does provide a completely uninterrupted signal – something Bluetooth just can’t do in water.

When wearing the earplugs and submerged in water, the high end sounded clear with a good amount of detail and the mids were present, if a bit recessed. However, whether I’m listening to rock or hip hop (or anything really), the bass is just too quiet. It’s there, but quiet enough to really impact the listening experience. If you turn up the volume on a song with a lot of low end, the headphones also have a tendency to distort. However,the highs and mids sound pretty decent, especially underwater, so if you care less about the music and more about using it with a coach or with classes, then you’ll hear everything clearly.

Using the headphones to access the classes in the water is such a novel and helpful experience, even if it seems like someone would have done it by now, that the price and my issues with the audio quality feel unimportant, not to mention that the fact that you can stream whatever you want in real time (well, there’s a three second delay intentionally built in) instead of loading MP3’s in advance as needed with any other decent pair of swimming headphones.

Zygo Z2: Specifications

Zygo Z2: Price and availability

• How much does it cost? $329 (about £250 / AU$480)
• When is it available? Available now
• Where can you get it? Available in the US

While those abroad will have to find a way to smuggle the Zygo Z2 out of the US to get it, those in the US can get it directly from the company for $329 (about £250 / AU$480). If you’re in Alaska, Hawaii, or Puerto Rico, you’ll have to also cover the cost of shipping (listed at $40 at the time of writing). They’re not available outside the US right now.

That’s a pretty hefty price tag considering that both the Shokz OpenSwim Pro and the H2O Audio Tri 2 Pro Multi-Sport cost much less, with the Shokz going for $179.95 / £169 / AU$299 and the H2O Audio going for $199.99 / £155.68 (about AU$310). Since those two headphones use built-in MP3 players for audio while in the water, they do sound a little better.

But that’s a little unfair to the Zygo Z2 as it offers a lot more than just a pair of headphones to use in the water. As I’ve mentioned, these are basically the Peloton of the pool. Yes, most of the features are locked behind a subscription, but that subscription is $4.99 a month for access to all the pool-focused exercises (including some weight training for the pool ones) as well as the walkie-talkie and lap counting features. No other swimming headphones do that, so the expense is worth it if you’re serious about swimming but want a little help.

Price: 4 / 5

Zygo Z2: Scorecard

Zygo Z2: Should I buy?

Buy it if...

Don't buy it if...

Also consider

How I tested the Zygo Z2

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

I spent a couple weeks testing the Zygo Z2 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, including the exercises and walkie-talkie.

After testing, it’s clear that these are ideal for serious swimmers, especially those who need a workout program to get the most out of their time in the pool. If you’re curious about how bone conduction headphones work, check out the linked article 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 December 2025

Zygo Z2: One minute review

The Zygo Z2 are part of a very small world of headphones, namely bone conduction models made for being used in the water. Yet even in this small space, they are unique. They’re not the only swimming headphones that you should consider, but they are the only ones that use a radio transmitter for listening to music in the water. There's no onboard MP3 player, so they're the only pair that you don’t need to sit down with in front of your computer, to manually load the headphones with music before heading to the pool.

And while that’s the big selling point you’ll see when you come across them on their website or on Amazon, the Z2s also offer a deep ecosystem within the downloadable app including a whole assortment of classes, along with features like a walkie talkie and lap counting, hidden behind an additional but low subscription fee. This makes the Zygo Z2 function like a Peloton for the pool. I’m not sure I’ve seen anything like that before.

Of course, they do come at a hefty price (and that’s before the aforementioned subscription fee), and the sound quality is not going to compete with the best wireless earbuds. But that’s to be expected with headphones that first, use bone conduction, and second, use radio transmission.

If you have a smartphone (and I’m going to assume you do), you might be aware that phones connect to devices via WiFi, data, and Bluetooth, not radio waves (even if you’re streaming a radio station through your phone, it’s coming to you digitally). Because of that little omission, the Zygo Z2 needs more than just a pair of headphones to function.

Enter the biggest headphones charging case I’ve ever seen in my life. This big black square measures a little under seven inches across and under three inches deep. There’s a flip lid hiding the headphones and earplugs, as well as the USB-C charging port, LED indicator, and the power / connectivity button. Most unique here though is the shark fin on the back that needs to be flipped up during use, like an antenna. Without it, there are no radio waves.

The headphones inside have an IPX8 rating, use bone conduction for sound, and come in the same imposing matte black as the charging case. On the back of the headphones, the volume up (also power) and down sit on either side of the Zygo logo.

Be aware when ordering the Zygo Z2 that they come in two sizes: Standard and Large. If you go by the size guide and choose wisely, you’ll end up with a snug fit. They never fell off, adjusted, or really moved at all. And despite their tight fit, I found them comfortable to wear.

I can get up to three hours’ of battery life during use, which is a bit lower than the competition (but likely to be more than enough for a single session), though using a completely different technology (the radio transmission) might have something to do with that. The charging case does at least have seven charges in it, so its overall battery life (when including the charging case) is about the same as other bone conduction headphones that have a charging case, and far more than those that don’t. For reference, many of the better bone conduction headphones last around nine to ten hours.

I feel obligated to share our "how do bone conduction headphones work?" article as this type of sound reproduction is such a niche within headphones. They’re really only popular when searching specifically for the best waterproof headphones or best running headphones, with a possible exception for office work. In essence, they sit on the bones in front of your ear, circumventing the outer ear, which make them great for use in the water.

It’s also why the Zygo Z2 (and most other swim-focused headphones) come with a pair of earplugs. They, like the charging case and headphones, come in a fetching Darth Vader black. They’re necessary for hearing the headphones, allowing you to focus on the audio vibrating through your cheek bones (It’s less weird than it sounds).

If you’re wondering how “Eye of the Tiger” gets from your phone to your ears, it starts with a smartphone using the Zygo app, which is then paired to the charging case (a simple Bluetooth pairing process) in turn automatically connected to the headphones via radio waves. The Zygo app showcases the full breadth of the Z2’s features. I can use the app to communicate with someone else wearing the headphones. It is one-way though, so the wearer can’t talk back (only really useful if you have a swimming coach).

To use this feature, you need to get the five-dollar-a-month subscription, which also includes lap counting and a large assortment of on-demand classes consisting of audio workout guidance. Having listened to a few, I found them easy to follow and understand as well as well-paced. I think this ecosystem of classes are also what separates the Zygo Z2 from other swimming headphones.

Unfortunately, the audio quality leaves a bit to be desired. Now it’s not bad and having the audio coming through radio waves does provide a completely uninterrupted signal – something Bluetooth just can’t do in water.

When wearing the earplugs and submerged in water, the high end sounded clear with a good amount of detail and the mids were present, if a bit recessed. However, whether I’m listening to rock or hip hop (or anything really), the bass is just too quiet. It’s there, but quiet enough to really impact the listening experience. If you turn up the volume on a song with a lot of low end, the headphones also have a tendency to distort. However,the highs and mids sound pretty decent, especially underwater, so if you care less about the music and more about using it with a coach or with classes, then you’ll hear everything clearly.

Using the headphones to access the classes in the water is such a novel and helpful experience, even if it seems like someone would have done it by now, that the price and my issues with the audio quality feel unimportant, not to mention that the fact that you can stream whatever you want in real time (well, there’s a three second delay intentionally built in) instead of loading MP3’s in advance as needed with any other decent pair of swimming headphones.

Zygo Z2: Specifications

Zygo Z2: Price and availability

• How much does it cost? $329 (about £250 / AU$480)
• When is it available? Available now
• Where can you get it? Available in the US

While those abroad will have to find a way to smuggle the Zygo Z2 out of the US to get it, those in the US can get it directly from the company for $329 (about £250 / AU$480). If you’re in Alaska, Hawaii, or Puerto Rico, you’ll have to also cover the cost of shipping (listed at $40 at the time of writing). They’re not available outside the US right now.

That’s a pretty hefty price tag considering that both the Shokz OpenSwim Pro and the H2O Audio Tri 2 Pro Multi-Sport cost much less, with the Shokz going for $179.95 / £169 / AU$299 and the H2O Audio going for $199.99 / £155.68 (about AU$310). Since those two headphones use built-in MP3 players for audio while in the water, they do sound a little better.

But that’s a little unfair to the Zygo Z2 as it offers a lot more than just a pair of headphones to use in the water. As I’ve mentioned, these are basically the Peloton of the pool. Yes, most of the features are locked behind a subscription, but that subscription is $4.99 a month for access to all the pool-focused exercises (including some weight training for the pool ones) as well as the walkie-talkie and lap counting features. No other swimming headphones do that, so the expense is worth it if you’re serious about swimming but want a little help.

Price: 4 / 5

Zygo Z2: Scorecard

Zygo Z2: Should I buy?

Buy it if...

Don't buy it if...

Also consider

How I tested the Zygo Z2

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

I spent a couple weeks testing the Zygo Z2 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, including the exercises and walkie-talkie.

After testing, it’s clear that these are ideal for serious swimmers, especially those who need a workout program to get the most out of their time in the pool. If you’re curious about how bone conduction headphones work, check out the linked article 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 December 2025