Zygo Solo review

The only swimming headphones to stream any content from your phone underwater

Zygo Solo swimming headphones
(Image: © Jamie Carter)

TechRadar Verdict

A one-off audio product ideal for swimmers and anyone else who likes an aquatic workout, the Zygo Solo is the only pair of swimming headphones that can stream content from a phone when you’re underwater. The headset is bulky and expensive, but its app full of coaching tips and tricks helps sink its rival Walkman swim players.


  • +

    Streams content underwater

  • +

    App includes coaching tips and workouts

  • +

    Easy to set up

  • +

    Excellent sound

  • +

    FM transmitter also works as a walkie talkie


  • -

    Requires a lot of gear poolside

  • -

    Works best with earplugs

  • -

    Headset has no playback buttons

  • -

    Charging case has no battery

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Editor's note

  • Original review date: July 2021
  • Original price $229 (£218.00, around AU$400.00)
  • Prices holding steady

Update: February 2024. Zygo is still unopposed three years on as the best premium option for in-pool workouts. The Zygo Solo vs H20 Audio Tri versus feature we did last year has a lot of points that remain relevant one year on: the FM radio transmitter means if you want to stream, Zygo Solo is the best option, especially if you want to stream guided workouts. The continued limited availability in the UK and AU is a big frustration, but otherwise for US swimmers, Zygo is the premium headphone set for you. The rest of this review remains as previously published.

Matt Evans
Matt Evans

Two-minute review

Is this the Peloton of the pool? With the success of that workout streaming service clearly in its sights comes Zygo Solo, a unique audio gadget for swimmers.

We’ve seen waterproof headphones and bone conduction headphones before, but not like this. Since Bluetooth can't penetrate water, all other swim headphones are little more than waterproof MP3 players (pretty much that music file format’s last stand). The Zygo Solo is different, and is able to stream content from a smartphone through water using an FM transmitter that can penetrate water.

It’s something of a 'hallelujah!' moment for swimmers, many of whom have by now experimented with the Sony Walkman NW-WS413 and then the Aftershokz Xtrainerz, both of which are good at what they do, but only play MP3s. Does anyone even have any MP3s anymore?

Zygo Solo equipment

The Zygo Solo kit consists of a headset, FM transmitter, stand and charging case, plus a pair of earplugs (Image credit: Jamie Carter)

A four-piece set consisting of headset, FM transmitter, stand and charging case, the Zygo Solo has a lot more hardware than your average pair of super-slim swimming headphones.

It works like this: your phone connects to the FM transmitter via Bluetooth and the transmitter to the headset via radio frequency. It’s easy to set up, though there’s definitely more physical equipment to deal with. It also means taking a lot of gear poolside. Fine in a private swimming pool, but not so great in a public pool where you’ll have to keep one eye on your stuff while you swim.

Nevertheless, committed swimmers with the right environment will adore the Zygo Solo. A long overdue audio upgrade for the pool, it’s surprisingly easy to use, offers great FM-quality sound and has hundreds of excellent on-demand workouts that can really change how you approach your swimming fitness. Or you can just listen to your own music, audiobooks or podcasts without having to drag-and-drop MP3 files prior to a swim.

How does Zygo Solo compare to its underwater MP3 player competitors? It blows them out of the water, of course – and it’s priced accordingly.

Zygo Solo price and availability

  • Out now
  • Costs $299 / £218 (about AU$400)

Available in the US, Canada and the UK in two sizes – standard and large – the Zygo Solo costs $299 / £218 (about AU$400) for the full package. A replacement headset costs $99 / £72 (about AU$150), while an external mic costs US$30/UK£22 (about AU$40), and is useful if a coach wants to use the FM transmitter as a hands-free walkie talkie.

If you want Peloton-inspired streaming swim workouts (comprising short and long audio workouts delivered by instructors and paired with music) then you also need to take out a Zygo All Access Monthly Plan, which costs $14.99 / £12.99 (about AU$20) per month after a 14-day trial.

In future Zygo tells us it’s planning metric tracking similar to that offered by the best running watches, leaderboards, and truly Peloton-style live classes. On Zygo’s website you can purchase an app gift certificate for an entire year for $149 / £108 (about AU$200), which gives you two months free.

Zygo Solo design

  • Headset weighs 66g
  • Waterproof to 2ft / 60cm
  • FM transmitter streams to 55yds / 50m

The Zygo Solo is, technically speaking, by far the most ambitious set of swimming headphones available. Predictably that means it comes with some baggage. The package consists of an IP68-rated waterproof headset, an IP67-rated (waterproof for 30 minutes) FM transmitter and stand, a pair of earplugs and a charging case.

While the Sony Walkman NW-WS413 and the Aftershokz Xtrainerz weigh 32g and 29g, respectively, the Zygo Solo headset weighs 66g. Why? It’s got a radio receiver as well as a battery inside that makes it possible to receive audio from the FM transmitter connected wirelessly to a smartphone.

The 101g FM transmitter itself is a figure of eight-shaped device that’s also waterproof, so it’s fine to leave it close to the water. Also included is a small 25g holder for the FM transmitter that keeps it upright, which extends its range.

Zygo Solo headset with transmitter

The Zygo Solo is considerably heavier than other swimming headphones due to its radio receiver (Image credit: Jamie Carter)

Meanwhile, the charging case itself weighs 450g, and 623g with both the headset and the transmitter inside. Resembling the kind of case you might find housing a pair of the best noise cancelling headphones, it’s rounded and compact, and fairly easily fits inside a swim bag. The headset also has an accelerometer inside, so expect activity tracking soon.

Zygo Solo setup

  • Connects via FM transmitter
  • Streams any audio from a smartphone

Despite a slightly convoluted hardware arrangement compared to MP3 swim players, the Zygo Solo is always easy to set-up. It takes a bit of getting used to. If you’re used to entering the pool with just a pair of goggles, or even if you’re used to donning an MP3 swim player, the Zygo Solo seems a lot to get used to.

The headset feels reasonably solid and unwieldy at first – it is, after all, more substantial than a basic swim MP3 player – partly because it’s designed to stay firmly in place during underwater turns. It’s chunkier because it’s got more hardware inside.

Man wearing Zygo Solo headset

The robust, chunky design of the Zygo Solo helps it stay in place during underwater turns (Image credit: Jamie Carter)

What’s really different about the Zygo Solo compared to MP3 swim players is that you have to have the FM transmitter and your smartphone poolside. That FM transmitter works to a range of 50 meters – so the size of an Olympic swimming pool – which is generous enough (it can also transmit to an unlimited number of headsets). However, if you’re used to leaving your phone in a locker and entering a neighborhood pool deck with just a towel, having to take a smartphone and an FM transmitter is a bit of a change.

The 50m limit applies only to swimming pools, with a half-mile range promised in the great outdoors. So you could get away with wearing a Zygo Solo while open water swimming, surfing, canoeing, kayaking, water skiing and even sailing.

Zygo Solo sound

  • Bone conduction works well
  • Sounds best with earplugs
  • Only the FM transmitter has playback buttons

Make no mistake about what Zygo is trying to do here; streaming live audio underwater is not easy. In fact, the tech it took two years to perfect. The Zygo Solo’s sound is good. Out of the pool it sounds a little tinny, but in the water it suddenly gets a lot of bass.

Let’s not overdo it; this is not audiophile quality, and overall the impression is (not surprisingly) of FM radio-like sound, with a little crackle and hiss now and again. However, at all times it sounds much better than any waterproof MP3 player. That is, if you remember to use the earplugs.

Close-up of Zygo Solo earpiece

The Zygo Solo uses bone conduction to send vibrations to your auditory nerve (Image credit: Jamie Carter)

Like the Aftershokz Xtrainerz the Zygo Solo are bone conduction headphones, using a technology that employs an open-ear design and transmits audio through vibrations in the cheekbones directly into the inner ear.

You don’t need to use the included earplugs, but if you don’t you’ll find that every time your ears are not immersed the quality of sound drastically changes. So for a more consistent experience it’s best to use the earplugs.

It’s possible to tweak the volume using + and - buttons on the headset’s right temple, and the FM transmitter has some too. It just about goes loud enough, but only the FM transmitter has skip track and play/pause controls, which is a shame. It means you have to make sure you have lots of songs/podcasts/content queued up, or keep the FM transmitter accessible by the side of the pool.

Man's hand holding Zygo Solo transmitter

Play, pause and skip controls are all on the FM transmitter, not on the headset itself (Image credit: Jamie Carter)

We found the headset to be reasonably comfortable when worn for long periods, largely because the bone conduction design leaves your ears alone, though it did begin to feel slightly tight after about half an hour. The advice is to put the headset on, followed by a swim hat, goggles and then earplugs.

As a nice bonus the transmitter doubles as a walkie talkie, so a coach can speak to a swimmer directly as they swim in the pool. What the headset doesn’t have is a microphone, so you can’t answer back … or make hands-free calls from the pool.

Zygo Solo companion app

  • Huge choice of pre-recorded workouts 
  • Excellent instructors and lots of music
  • Live classes and activity tracking promised

The Zygo app for iOS  and Android has had a lot of investment in it and is arguably the best reason to invest in Zygo Solo. It’s not free, but there’s a huge choice of classes and activities inside. As a few random examples we found a 20-minute beginner-level tutorial in learning backstroke, an intermediate 30-minute HIIT workout and a ‘fun’-grade 25 minute DJ drill set to music.

Each one has excellent instructors and a lot of music, the latter the result of various licensing deals struck between Zygo and the music industry.

We counted over 50 drills, which seems good value, which can be browsed on a timeline but also by specific genres, such as ‘strengthen and lengthen’, ‘5 days of fitness’ and ‘your first sprint triathlon’. It’s best to download them on WiFi within the app before hitting the pool.

Zygo Solo app screenshots

The Zygo Solo mobile app includes instructor-led workouts, with licensed music (Image credit: Jamie Carter)

However, the app does need a queue so that lessons and drills can follow-on from each other. Since some are only a few minutes long you can easily find yourself completing a drill and then swimming in silence.

In future Zygo tells us it’s planning to go full-Peloton and add live classes and leaderboards, with new software incoming that will use the built-in accelerometer to track your activity in the pool.

The app works independently of the device, so in theory you could just subscribe to the app and use all the workouts … though the Zygo Solo is so far the only way to stream content underwater.

Zygo Solo battery and charging case

  • Headset lasts for three hours
  • Charging case uses micro USB not USB-C
  • Charging case doesn’t hold a charge

Inside the Zygo Solo headset is a battery that lasts for three hours, and the transmitter lasts for around six hours. Sadly the hard-sided charging case itself doesn’t hold a charge, but if you snap both gadgets into place in its molded interior, both nestle up against precisely-placed connectors and begin charging automatically if the case is hooked up to power via a micro-USB cable.

Zygo Solo headset and transmitter in charging case

The headset and transmitter are charged by placing them inside the case, which is powered by a micro-USB cable (Image credit: Jamie Carter)

It’s a shame the case doesn’t contain a battery of some kind, and micro-USB also feels slightly outdated given the popularity of USB-C.

Buy it if

You want to get more out of swimming
If swimming is your sport and you want to get as much from it as possible then you’ll love the Zygo app’s workouts and coaching tips. For those who swim casually but get bored, the ability to listen to music, podcasts and audiobooks is a game-changer.

You’re done with MP3s
It’s not 1999. Why should you be side-loading anything with MP3 files on a regular basis, as most swim MP3 players insist upon. Zygo Solo lets you stream any content from your phone underwater.

Don't buy it if

You can’t keep an eye on your stuff
The Zygo Solo requires that you have both your smartphone and the radio transmitter pool-side. If you’re swimming in a public pool then keeping an eye on a bag full of expensive stuff might not be easy. That will depend on the size and layout of the pool you use.

You’re a diver
It may be unique, but the Zygo Solo is designed to stream audio through shallow water only. Its transmitter is able to stream to a headset up to 2ft / 60cm below the surface and to a distance of about 55 yards / 50 meters. 

Jamie Carter

Jamie is a freelance tech, travel and space journalist based in the UK. He’s been writing regularly for Techradar since it was launched in 2008 and also writes regularly for Forbes, The Telegraph, the South China Morning Post, Sky & Telescope and the Sky At Night magazine as well as other Future titles T3, Digital Camera World, All About Space and Space.com. He also edits two of his own websites, TravGear.com and WhenIsTheNextEclipse.com that reflect his obsession with travel gear and solar eclipse travel. He is the author of A Stargazing Program For Beginners (Springer, 2015),