Garmin’s Descent Mk3i dive computer has been touted as something of a game-changer for its messaging capability – but does it live up to the hype? DIVE’s editor took one to Sharm for a review
I’ve been extremely interested in Garmin’s Mk3i smartwatch-style dive computer since its launch, primarily for its underwater diver-to-diver communications capability, when paired with Garmin’s Descent T2 transceiver.
At a price point well beyond my personal budget, it was never a realistic option for a purchase, but when offered the chance to try one out, there was no realistic possibility of turning it down!
Out of the box and first impressions
I was sent the 51mm model (there is also a smaller 43mm version), which came with a USB charging cable and, in my case, a standard-length black silicone strap plus an extra-long spare for thicker exposure protection. A model with a titanium band is also available for around £150 extra.
It is a good-looking bit of kit. It’s solidly built and – given the computer had been worn by other journalists prior to me – it was pleasing to note that the anti-scratch-resistant crystal of the face lives up to its name. The watch face is changeable, but I like the aesthetic of the default analogue display.
There are five buttons in total, and all are easy to use, at least with my ungloved hands. One of them even operates a flashlight, which I thought was a bit silly at first, but which I found myself using quite extensively in the dark!
One test I apply to new devices is ‘can I use it without referring to the manual’, which is the only real measure of whether or not an interface can be described as truly intuitive. (Obviously, if you actually buy a dive computer, please Read The FULL Manual before going anywhere near the water!)
For nerds like me, then yes, the Mk3i is reasonably intuitive, but the feature set is so dense that ‘wading’ would be the descriptor I would use for cycling through its menus – bear in mind it comes programmed with a full suite of Garmin’s health and fitness tracking apps, GPS navigator and digital wallet on top of its smart device capabilities.
Some of the buttons’ long-press functions can be reprogrammed as hot keys, which is useful, but at the surface, navigation is best done by scrolling the touch screen through the list of apps, settings and ‘glances’ (shortcuts, basically).
There’s still a lot to navigate, but configuration is inestimably more convenient using the Garmin Connect app on a smartphone with its larger and less cluttered interface.
The short version, however, is download and RTFM.
Using the Garmin Mk3i underwater
Prior to getting my hands on one, I thought that smartwatch-style dive computers occupied a space that is too small to be a dive computer and too large to be a watch. Both of these notions were dismissed after making my first dive using an Mk3i and wearing one above the surface for 24 hours.
For the purposes of this review, I was sent a second computer and a pair of Descent T2 transceivers so that my buddy and I could play with the communications features.
The T2 screws into your first-stage regulator’s HP port (or short HP hose, if you prefer) and is activated by opening the tank. Pairing through Mk3i’s networking menu is straightforward, as any transceiver in the vicinity will be automatically recognised. Each is identified through its serial number (which could be a bit larger), and can be renamed so you know which belongs to whom – a bit fiddly through the computer menu buttons, but very easy through the Garmin app.
The display is bright, clear and easy to read at all times. The main screen can be customised to show an extra field on top of the basic dive data, and a second screen can be populated with additional data points such as compass bearing, maximum depth or CNS level, depending on what you’re doing.
Everything on the display is nicely colour managed with green for food and red for bad, with alarms for transgressions both audible and haptic.
You can pair up to eight transceivers with a computer and set two tank pressures to be displayed on the screen by default, with the others accessed through the menu system if present, enabling you to keep tabs on up to eight divers’ air supplies.
Buddy depth, distance and direction are also available – I couldn’t really test this with any rigour as I was diving in the Red Sea with visibility greater than the 30-metre range of the Mk3i’s comms, but I can say it’s fairly accurate, based on what I could actually see.
Very importantly, battery life is excellent. I wore the computer continuously for the better part of two months and it needed charging once after starting from a full charge, even with ten dives included.
Messaging and comms
Messaging and networking are the most unique selling points of the Mk3i and its siblings. For those who may have concerns, no, you can’t WhatsApp or post to social media, and you don’t share your dive data unless you specifically choose to do so.
Messages are selected from a list of presets covering a variety of scenarios, starting with basics such as ‘Are you okay?’ or ‘Follow me’, to discussions about remaining dive or deco stop timing. A programmable quick-access menu enables divers to access those most likely to be important for any given dive.
Radio waves don’t work underwater, so Garmin uses its own proprietary ‘SubWave’ sonar protocol, which travels a lot further, but much more slowly. Communication requires a direct line of sight within at least 30 metres, but it can take up to 45 seconds for a message to be sent, depending on distance and the orientation of your respective transceivers.
I timed some as within 5–10 seconds, but one or two were definitely closer to the 45-second mark, even without a huge amount of buddy separation.
The gin-clear Red Sea and two buddies very articulate with hand signals was not the best testing regimen, but I could definitely find utility in attracting her attention without having to hammer divots into my tank or waggle an obnoxious dolphin shaker.
In a group, especially as a guide, messaging and air supply checking would have been extremely useful, even more so with the 2025 launch of Garmin’s Descent S1 buoy, which enables direct communication between divers and their surface support.
It would be nice to be able to add customisable messages (which I know is on Garmin’s list of things to do), but it’s a good start in something that is likely to become a must-have for dive computers over the next decade.
There is one fly in the ointment, however, and that is the fact that the T2 transceiver, using sonar as it does, generates a persistent set of regular clicks. A bit like a distant dolphin might sound if it was communicating through a loudhailer. I thought at first it was just the sound of the reef, but it became clear over time that it wasn’t. I wasn’t exceptionally bothered, but my buddy found it infuriating. Caveat emptor.
The Garmin dive app(s)
You need both Garmin Dive and Garmin Connect to take full advantage of all the Mk3i’s features – the pair operate together seamlessly for the most part, and it’s much easier to footle about with the features through the app rather than stabbing buttons on the computer.
The Dive app is great and automatically populates itself with all relevant dive data, gives you a great breakdown of things like your gas consumption rate, PO₂ and tank pressure, adds in GPS mapping data and a whole bunch of stats, plus plenty of custom spaces to fill in with gear, weight and buddy data.
My only irritation with the app was that it occasionally logged me out for no reason. This is a minor annoyance when you’re assembling your gear, but it’s a very major annoyance when you’re already in your wetsuit and your phone is packed away in your drybag.
Conclusion
The Garmin Mk3i is an excellent dive computer and smartwatch, with a few caveats. It’s capable of single- and multi-gas diving, apnoea and CCR diving and is rated to 200m – but even though I’m not a tech diver, I’m not sure, based on what I do know, that I’d want to use it as a primary computer for anything more than recreational tech diving. Hardcore techies will want to look at Garmin’s Mk50i for the tough stuff.
As an all-out everyday smartwatch and recreational computer it excels, but the big sticking point is, of course, its price. The Mk3i starts at £1099.99 for the smaller, 43mm version with a silicone band and tops out at a whopping £1599.99 for the 53mm model with a titanium band.
You can add on another £430 for the T2 transceiver; up to £150 more for a heart rate monitor and an optional subscription to Garmin Connect if you want to take advantage of the computer’s full set of premium features.
Is it worth the money? For all the tech it packs – and it goes without saying that Garmin is a premium brand – then yes, probably, but for most divers it’s kitchen-sink overkill. I’d love to see a ‘Lite’ version at a lower price point with just the essentials, and then perhaps additional features added through paid-for updates if and when they become useful.
Honestly, though, I love it, and I’m sad I have to send it back to Garmin (no, we don’t get to keep top-tier gear in return for favourable reviews!), but I’m going to buy an extra lottery ticket this weekend just in case….
Verdict: Splash if you have the cash, but don’t break the bank if you’re on a budget.
