Review of the Garmin Descent MK2i
The long awaited Garmin Descent MK2i dive watch is here! I have my hands on one of these new computers, and would like to share my thoughts on it. How does it compare to the Descent MK1? How well does it work as a dive computer? How does it compare to the Shearwater Teric? Is the price point worth it? Let's find out.
For those unaware, Garmin came out with their first diving watch, the Descent MK1 several years ago. It’s a watch-style fitness device, made for scuba divers. As a runner I had always been a fan of Garmin fitness products, however I was very nervous as to how their first dive computer would function. As it turns out the diving 'app' as Garmin calls it, is quite outstanding and well thought out. Much has already been written about the Descent MK1. So the question is, how does the MK2 improve on this?
The 2 computers are almost identical, in size, shape and weight. For fitness users, the Descent MK2 adds a few new things like pulse oximetry, and some new metrics for your workouts.
The biggest addition for the Descent MK2i (the “i” stands for integration, in case you couldn't figure that out) is what Garmin is calling the subwave network. This means your wireless air integration transmitters use a sonar-based communication technology instead of the radio-frequency method used by most other computer manufacturers.
Subwave is good news and bad news for some divers. The bad news: the wireless transmitter is proprietary to Garmin. Any existing transmitters you may have from other dive computer manufacturer are incompatible with the MK2i.
The good news: Increased range and signal strength underwater, as well as support for up to 5 transmitters. Garmin claims up to a 10 meter or 30 foot range, which from my limited experience with it, seems actually conservative. The combination of increased range and the number of supported transmitters could actually allow one to monitor not only their own air pressures, but also the air pressures of those around them - something the MK2i supports.
In theory, this idea is really cool. For a dive center willing to spend the money on a bunch of transmitters, a dive instructor or dive guide could conceivably monitor the tank pressures of a group of student's or DSD's. In reality however, I don't see many dive centers willing to cough up almost $4,000 worth of gear just to help monitor tank pressure, and the odds of having all of your paying guests similarly equipped are probably nil.
Garmin isn’t unique to the idea of sonar pulses for transmission of air integration data. Fans of the dive computer company Liquivison will remember that the Lynx dive computer also employed a similar idea. The technology allows for some amazing potentials, such as location, ranging, and the ability to send text messages. Yes, I know most of us dive to escape the nagging of text messages, but for emergency or diver recall situations, this could be useful. Neither location services or messaging have been implemented on the Garmin, but it's something that could be at a future date.
It's worth noting, that Garmin is making 2 versions of the Descent MK2 - with and without air integration. The “i” version is available only in a titanium bezel, while the standard MK2 is available in stainless steel and titanium, but only the MK2i will support wireless air integration.
The Garmin MK2/MK2i diving modes
For those unfamiliar, Garmin’s fitness activities are programmed into their watch in what they call apps or activities, and the diving modes are no different. There are dozens of pre-loaded apps and activities for any outdoors enthusiast, but for the purposes of this review, we will stick with the ones related to diving. Both the Descent MK1 and MK2/MK2i support the following dive activities:
Single Gas - This is intended for most recreational, single tank divers, although it does offer the ability to change to an alternate gas mix while underwater of up to 100% oxygen, and will support full decompression, should you inadvertently miss your NDL time. You can enable or disable a missed deco lockout period.
Multi-Gas - This mode is for open-circuit technical divers, and allows for up to 6 preset gasses of any oxygen and helium combination for back gas and decompression mixes.
CCR - This mode is for rebreather divers of course, and allows for constant PO2 decompression calculations with multiple diluents, along with up to 6 saved bailout gasses.
Gauge - A simple gauge mode for those who wish to know depth and time.
Apnea, and Apnea Hunt - these are Garmin’s freediving apps, but as the world’s least knowledgeable person on freediving, I can’t comment on them, how they work, or the difference between the modes.
Activities and apps can be added, sorted, or made 'favorites.' Both Garmin and 3rd party developers make all sorts of apps that one might find useful. You can remove the activities you don't do, and keep a short list of things you actually do.
In all diving modes, Garmin uses the Bühlmann ZHL-16c algorithm, and allows the user to adjust their conservatism using gradient factors. Garmin offers 3 preset levels of conservatism - high (35/75,) medium (40/85,) and low (45/95,) as well as a user-customizable setting. This can even be changed underwater.
In every diving mode, 3 screens may be accessed:
Your main diving screen displays the basics - depth, time, NDL (or 1st deco stop) and water temperature. If you’re diving the CCR mode, it will also display your setpoint, and your diluent mix. If you have air integration, the temperature line can be replaced with up to 2 tank pressures. It will even display this in CCR mode.
From each main screen, the user has 2 options. Pushing lower right will bring up a menu allowing the user to change certain parameters. In open circuit mode, one can change the gas mixture, adjust their deco PO2, or edit their conservatism.
In the CCR mode, a lower right push will allow even more options, including switching setpoint (this can also be done automatically by depth,) bailing out, adding or editing gasses, editing setpoints, and editing conservatism.
From the main menu, pushing the left lower button will scroll you to the compass screen, where it will bring up a heading, and an animated compass strip, along with your NDL, depth and time.
Pushing the left lower button again, will scroll you to the third screen, which offers some additional information. Here we can see the time of day, time to surface, water temperature, max depth, battery level, NDL, current depth, and dive time. If you’re in the CCR mode, a slightly different layout it shown, where it shows OTU level, and CNS percentage in lieu of max depth and the temperature.
Those with air integration enabled, can access a 4th screen, which is the AI screen. Here it shows your surface air consumption rate, your estimated air time remaining, tank pressures (which can be named,) NDL, depth and time.
Previous versions of Garmin firmware did allow for the heart rate to be shown in the 3rd diving screen. This of course leads everyone to ask the question, how well does the heart rate work underwater?
In my experience, not terribly well. Even though the new firmware doesn’t show the heart rate anymore (it may on the freediving modes, I’m not sure,) it still does log your heart rate. This graph shows my heart rate on one of my recent dives, and you can see how erratic the data is. Obviously the watch needs to be on your bare wrist, for this to even work at all.
How does it compare to the Teric?
Having owned a Shearwater Teric, a Descent MK1 a now a Descent MK2i, I get asked this question very often. Divers always want to know, which one is better? Which one should I buy?
I’ll start this off by saying that everyone has their own needs from a dive computer, and mine are a bit different from most divers. All of my diving is done on a rebreather which has its own primary computer. I wear the Garmin as a timepiece first, as a fitness device second, and a dive computer last.
Since the Shearwater Teric doesn’t offer any fitness apps, it’s not really a direct comparison. So for those who are not into fitness, I’ve tried my best to compare the 2 over a range of different categories where they are similar. This comparison is for the Shearwater Teric vs the Garmin MK2i, and use of a single air transmitter.
The MK2i is $1,499, plus another $399 for the transmitter, bringing the cost to $1,898 USD. By comparison, the Teric comes in at $1,095 plus $350 for the transmitter, making your total cost $1,445 USD.
Advantage - Shearwater
I have to admit, when I got my first Descent MK1, I wasn’t expecting much out of the diving apps, however I was pleasantly surprised at how well thought out they were, and how well they worked. I would highly recommend anyone to use this as their sole dive computer.
However, the Teric has a certain elegance of its user interface, display and customization that the Garmin doesn’t have. Changing settings, navigating the menus, and diving the Teric can all be done intuitively without ever reading a manual. This comes no doubt from the fact that the founder of Shearwater is a lifelong diver, and years of constant product refinement over their other computers.
Advantage - Shearwater
These 2 computers use totally different displays, each one with its advantages and disadvantages.
The full line of Garmin Descent computers (MK1, MK2, MK2i) use a sunlight-visible, transflective memory-in-pixel display, sometimes known as a transflective liquid-crystal display. This is occasionally called e-ink, although that’s not technically correct. The advantages of this display are that it is very easy to read in bright sunlight and it has very low battery consumption. The downsides are that you cannot read it in darkness without a backlight, and the resolution of the display isn't as nice. With the backlight on, the power draw is of course higher and Garmin allows for user-defined brightness settings on all of the Descent computers. Here in the sunny clear water of the Cayman Islands, I still find I need the backlight on most of the time to see the display underwater. Garmin did recognize this fact, and there's an option to keep the backlight on during a dive, at a lower brightness, thus saving power.
The Shearwater Teric uses an organic light-emitting diode, or OLED display. OLED displays look amazingly bright, with sharp contrast and are super easy to read underwater and in dark light. The Teric’s OLED is bright enough to read in bright light, but not as easy as the Descent. OLED's also draw a huge amount of power.
Advantage - It's a wash. While this may sound like a copout, it's not. It really comes down to this - the Descent is better in bright light, the Teric is better in dim light. Neither work in all light conditions perfectly. With either computer, there will be some part in the day where you have trouble seeing the time without pushing a button. Not a huge deal, unless your hands are full. Garmin does have a setting enabling one to automatically turn on the backlight when you flick your wrist, however I find it doesn't work reliably.
This video clip shows the comparison between the Garmin Descent Mk2i display and the Shearwater Teric when viewed in bright sunlight.
This is a slam-dunk win. The Teric’s OLED display draws so much more power, with reasonable use, you need to charge it almost daily. With power conservation, little diving, and the display mostly off, you can make it last a few days, but it can’t compare to the Descent, which can last weeks without charging.
On a recent liveaboard trip on the Cayman Aggressor, we did 5 dives per day over 5 days. My girlfriend, wearing a Teric, had to charge the battery during lunch, and at night. I charged my Descent MK2 once mid-week for the entire trip.
Advantage - Garmin
The Teric uses inductive charging and comes with a wireless charging cradle. Some have reported the charger to be finicky, however the Teric will work with many different charging mats. Odds are the charing mat you use for your phone will be able to charge the Teric, in a pinch.
The Descent MK2 and MK2i use a proprietary USB charging clip. The Descent MK1 used a spring cradle, which I found difficult to use when you are in the dark and half-asleep. The MK2 and MK2i use a clamp-style which is easier and more reliable, however if you lose it - you’re screwed.
Advantage - Shearwater
Left, the Garmin MK1 charger. Right, the Garmin MK2 charger.
With the Teric you’re limited to the 3 default watch faces. At some point, Shearwater may add a 4th and 5th, or even another dozen. However this doesn’t compare to the hundreds of watch faces made by Garmin, and their 3rd party developers. With the Garmin, you can customize the display to show exactly what you want, in the exact style you want.
Advantage - Garmin