My Detailed Initial In-Water Impressions of Garmin Mk3i

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chrisjur

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Location
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So, I figured I would take a few minutes to write up my initial impressions of the Garmin Mk3i after my first dives with it since there don’t seem to be any in-water reviews on Scubaboard yet (In fact, I find it odd that there are still very few reviews anywhere on the Internet), My review will focus primarily on the differences between the experience diving with “old” Mk2i vs. the Mk3i. I hope it will be helpful to those who have used the Mk2i and are considering an upgrade or those who might be on the fence about the Mk3i versus other options on the market (including the currently discounted Mk2i). I will not focus on the overall features of the Mk3i because many videos on the web go pretty deep into this.

Background
I’ve been diving the Mk2i over the past year and have 90 dives on it. I’ve pretty much brought it through the wringer on open-circuit dives - shallow, deep, multi-gas deco, and gauge-only. I don’t dive CCR, so I can’t comment on that. I dive with the Garmin T1 Transmitter for air integration (for reference, the Mk3i was introduced alongside the new T2 Transmitter - more on that later). Most of my diving is warm water wreck diving in Florida, but it’s come with me to the Bahamas, Cozumel, Maldives, and French Polynesia.

So, full disclosure going into this: I have really liked the old Mk2i. I feel that the functionality and the software are robust, the unit is rugged as hell, it has amazing battery life, and it has a good online services ecosystem with Garmin. The bottom line is that the Mk2i + T1 transmitter did not let me down over 90 dives. I also like the wristwatch form factor, although I am highly aware that this is a very personal preference and a frequent topic of debate among the community - I won’t go down that rabbit hole. So, of course, I was excited to try the new Mk3i given my good experience with Garmin over the past year.

IMG_1553 2 Medium.jpeg

[Older Garmin Mk2i on the left, new Mk3i on the right]

Initial Impressions
It’s probably no surprise that I’ll start with the screen. The AMOLED screen in the Mk3i is a MAJOR improvement over the Mk2i. It is bright, crisp, and clear and doesn’t leave anything to be desired. According to the specs, Garmin had finally cracked the code when it comes to offering this type of screen while simultaneously preserving the amazing battery life that the Mk2i offered (actually, improving on it in this new model - I’ll speak more to this in a bit). The Mk3i now also comes with a touchscreen that allows you to tap and swipe the screen. However, I have rarely used it. The button-based navigation scheme introduced in the Mk2i has carried over to the Mk3i, and it’s been burned into my brain at this point, regardless of how archaic it can be. The screen size has not changed, but it appears slightly larger due to the Mk3i’s slightly thinner bezel.

The unit itself feels rugged and well-built. It’s a tank, but it doesn’t feel heavy on the wrist for me. It looks and feels like a very premium product. The new strap looks and feels identical to that on the Mk2i, and I like how it’s both somewhat soft but still very strong. The tactical push of the buttons feels the same, but they have added some new type of safety guard to the Mk3i, presumably to protect the most important “Start” button, which can be used to stop the dive or switch gasses, among other things.

I think the last major physical attribute of note is the addition of the LED “flashlight” to the case edge just above the top strap. The light is surprisingly bright for what it is, but I’m not sure it’s a feature I’d see myself using a lot - perhaps while on the boat during the occasional night dive. To be clear, this is pretty useless underwater. It’s a cool addition, but not one that excites me too much.

IMG_1688 Medium.jpeg

[New Mk3i on the left with "button guard". Mk2i on the right.]


Software and Setup…and lessons learned after Dive 1!
The setup was easy, as you would expect from Garmin. I would like Garmin to pull settings and preferences from the cloud every time you set up a new device, similar to what Apple does for most devices. Unfortunately, you must set the Mk3i up from scratch, even if you have a previous Garmin dive watch. Unlike the previous computers, the Mk3i will now default to the “Big Numbers Mode” screen layout. For about my first 70 dives on the Mk2i, I avoided this screen layout because I thought “more data was better”. But I often found myself squinting at the screen and searching for what I was looking for. In reality, I think the Big Numbers layout is more practical, easier to read, and covers everything you’d need: Depth, gas type, NDL, PO2, Run time, descent/ascent indicator, air-integrated PSI and a revolving upper “panel” that can be tapped to rotate in a few other data elements, such as water temperature. The screen contents will dynamically change depending on the circumstances. For example, NDL is replaced by a bright green box that contains your safety stop countdown once you hit 20 feet or your customized depth trigger.

I should note that I did not buy the new Garmin T2 transmitter and decided to use my “old” T1 transmitter instead. (See below, where I talk more about transmitter compatibility) However, I missed one big key setup item, which is not explicitly mentioned in the documentation: You must set up all cylinder attributes if you’re using air integration, even if the transmitter was previously set up correctly. This makes sense when you think about it, but in my head, I just assumed that the transmitter would know that I was using a 100 cu. ft. tank with a working pressure of 3442psi because that is how it was always set up. However, the transmitter itself is pretty dumb and just sends the current PSI data to the computer, which is the real brain of the operation. Garmin defaults the transmitter settings to 3000psi working pressure and a cylinder size of 0 - yes, zero. As a result, my numbers were screwed up after my first dive, most notably my computed SAC and recorded cylinder attributes in the computer’s Dive Log and Garmin Dive app. During my surface interval, I changed the AI settings to the correct cylinder attributes, and everything worked correctly on the second dive. (Suggestion to Garmin to set the default AI cylinder settings to something typical like 77 cu/ft. + 3000psi for an AL80)

Automatic syncing to the online Garmin Connect service and Garmin Dive app worked right after setup. When I grabbed my phone during my surface interval, I had already been notified that the first dive was uploaded and available. The Garmin Dive app is one of my favorite components of the Garmin offering. It's a data nerd's dream

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Dive Features and Performance
Well, believe it or not, there’s not a ton to say here. While underwater, the Mk3i performs almost identically to the Mk2i, which is good. The biggest change, of course, is the screen. The Mk3i’s screen is like a beacon in the dark compared to the Mk2i. It made me wonder if the Mk2i’s screen was just really bad or if the Mk3i’s screen is just really great (I think it’s a little bit of both). I did dive with both of them on separate wrists, and the comparable difference in screen brightness and clarity was night and day (no pun intended). The only other noticeable difference to me was the strength of the vibration on the Mk3i anytime an alert occurred. I feel the vibration is much stronger on the Mk3i, but maybe I was extra sensitive today.

Overall, the dive performance was excellent, and I felt like I was just using a refreshed version of the Mk2i instead of a completely new computer. And I say that in a good way. The Mk2i is solid and stable and it appears that Garmin has mostly taken a “leave good enough alone” approach with the Mk3i.

One new feature that Garmin has touted is the new DiveView Maps. These maps provide information about depth, terrain, and the location of popular dive sites. I did play with this a bit, but I’m struggling to understand its practical use. The data is too limited, and the screen is too small for real dive planning. I also found the interface to be complex. Perhaps, if you’re unfamiliar with an area, you can pull up the map to help discover new dive sites. However, this would assume that you’re on your own boat and have the luxury to explore sites on a whim. It also appears that the dive sites utilize a database that Garmin has used for a long time, which automatically displays dive site locations in your Garmin Dive app. This is a very neat feature when it works. However, I have found that many popular sites here in South Florida are either not in the database or are not picked up after you’ve completed a dive.

Diving with Both Computers at Once (Mk3i and Mk2i) + Multi Transmitter Support
So, I wasn’t just diving with both the Mk3i and Mk2i to experience the differences side-by-side. I always dive with redundant computers, and this will be my new setup moving forward. A few observations should be noted about this type of setup: First, the T1 and T2 transmitters are forward and backward-compatible with all Garmin computers supporting AI. The main difference is that the new messaging feature that Garmin has touted requires T2 transmitters (which is why I didn’t test this feature). Garmin publishes a good compatibility chart here but the reality is that everything just works well with each other. After pairing my transmitter with the new Mk3i, my primary tank pressure could easily be viewed on both computers simultaneously (and they were always exactly the same PSI number).

Furthermore, both the Mk3i and Mk2i can connect to multiple secondary transmitters (max of 5 cylinders with the T1, 8 with the T2). This could be your buddy’s tank or your second post if you’re diving doubles and are a gadgethead who wants this. Your buddy can then set up his cylinder as his primary, and you can set up his transmitter as a secondary. The computers have separate screens allowing you to see your connected transmitters. However, you can also display two transmitters on the main screen, which is very nice. I tried this myself today when a dive buddy allowed me to pair his transmitter and vice versa. We only dived together for about 5 minutes to try it out, but it was quick to set up and worked flawlessly until we were about 15 feet apart (maybe more; I’m bad at judging these things).

If you are wearing two Garmin computers, they will both upload to the cloud by default. This means that you will have duplicate dives in your Garmin Dive and Garmin Connect Dive logs. You should know that each watch has a separate dive counter, which you can reset to whatever you want. For example, my first dive with the Mk3i was uploaded as dive #1, while the Mk2i uploaded that same dive as dive #91. I then changed the Mk3i dive to 91, and both computers subsequently numbed the next dive as Dive #92. You can decide if you want to delete one of the dives, and there’s probably a way to stop one of the computers from uploading altogether if it really bothers you (I have not researched this).

Another interesting thing to note is that all the statistics about my dives were identical between the two watches, including things like N2 loading, OTUs, etc. This is unsurprising since they probably run the same code for these core algorithms. One quirk to note is that the Mk2i consistently showed longer dive times by up to 20 seconds. Is this a setting thing? Are they using different types of depth sensors? I'm not sure, but it's not a big deal.

Battery Life
The battery on these Garmin computers is nothing short of amazing. Back in December, I kept forgetting to charge my Mk2i in the Maldives, but the computer still had more than 40% battery life after three days and six dives. Luckily, it appears that Mk3i hasn’t lost anything regarding battery life. A few quick stats:

8:00am: I turned the Mk3i on, and the battery was at 97%. Started wearing it for the day.​
2:26pm: First dive begins, run time of 41:25​
3:53pm: Second dive begins, run time of 38:11​
5:25pm: Captured photo of computer battery below. Battery is at 93%​

After two dives and nine hours on the wrist, it ate up 4% of its battery. That’s pretty good.

There are a couple of important things to note. First, I do NOT wear these computers outside of dive days. They are not everyday smartwatches for me, so your mileage may vary depending on your usage characteristics. Second, I don't have the screen set to "always on", which means that it wakes up when you turn your wrist - this does save on battery life. Finally, I *do* have it set to the brightest screen setting, which drains more battery than its slightly dimmer default setting.

IMG_1685 Medium.jpeg

[Mk3i after 9 hours on the wrist and 2 completed dives.]

Summary
So, I’m not going to discuss competitors - we all know what’s out on the market, and we know that Garmin and Sheerwater are most certainly going head-to-head when it comes to diving computers in the wristwatch form factor. I also know from my journey and that of friends that people will jump ship from one brand or form factor to the other. These are all great computers, and you’ll just have to research what is best for you. I won’t examine issues concerning wristwatch form factor, price, or specific brand attributes.

That said, the Mk3i is an excellent computer with good improvements over the Mk2i. Of course, the screen is the real difference here. The better battery life is great, especially given the new screen technology - it’s best-in-class.

So, if you were on the fence, should you buy it?

This should certainly be a contender if you’re looking for a new dive computer. It’s a top-tier dive computer, and I think it’s suitable for most divers (I can’t speak to how this would be valuable to CCR divers, so I’ll ignore that and assume you will be running a Sheerwater controller, anyway). You can save $200 today if you buy the older Mk2i while supplies last, but I think you’ll be disappointed in yourself if you go that route.

If you have a Mk2i (or another computer brand) and want a secondary, redundant dive computer, you should consider the Mk3i. I’m very happy with my own approach here.

If you have a Mk2i and are tempted to upgrade to the Mk3i, replacing your Mk2i, I don’t think the decision is obvious. At the end of the day, the Mk2i is still a great dive computer, and it will continue to serve you well for years. Yes, you’ll like the Mk3i better, but you might like $1600 in your pocket even more. There’s no denying that Garmin computers are at the top of the market regarding price point.

Safe Diving!
 
Awesome review. I can confirm, as a daily wearer on land with a lot of GPS tracking usage, the battery life and screen quality are as advertised. I love this watch.
 
Question as a current Mk2i owner - are there any changes to the user-programmable dive fields in single gas/multi-gas dive mode? One of my only complaints about the Mk2i is that you can't add some fields (average depth!) to the customizable screens.
 
Question as a current Mk2i owner - are there any changes to the user-programmable dive fields in single gas/multi-gas dive mode? One of my only complaints about the Mk2i is that you can't add some fields (average depth!) to the customizable screens.
I have not gotten there yet. As you've implied, the dive field configuration capabilities of the Mk2i and the process to change what they do support is somewhat maddening, so I didn't want to go down that rabbit hole. I do feel, however, that what's displayed on the Mk3i "Big Numbers" screen is very sufficient for what I need, so I'm not sure I will want to change it. However, I'll play around with it this week.

Is there anything specific you have in mind? I will give it a try.
 
Question as a current Mk2i owner - are there any changes to the user-programmable dive fields in single gas/multi-gas dive mode? One of my only complaints about the Mk2i is that you can't add some fields (average depth!) to the customizable screens.
Here's a video that I found. It looks similar to the Mk2i, but perhaps they've expanded the fields that are available/changeable.

 
I have not gotten there yet. As you've implied, the dive field configuration capabilities of the Mk2i and the process to change what they do support is somewhat maddening, so I didn't want to go down that rabbit hole. I do feel, however, that what's displayed on the Mk3i "Big Numbers" screen is very sufficient for what I need, so I'm not sure I will want to change it. However, I'll play around with it this week.

Is there anything specific you have in mind? I will give it a try.
Adding Average Depth (available in Gauge mode) to literally any field in Single or Multi-gas mode is what I’d love. At the moment, you have to pick between diving in computer mode, or being able to access Average Depth for ratio deco on-the-fly.
 
Good write up! I'm hopefully going to upgrade my MK2i here in the next few months, and I'm glad to see the screen looking a lot crisper.

Are there any real differences between the T1 and T2 transmitters? I already have 2x T1 transmitters, and I haven't really seen anything on Garmin's site explaining why one may be better than another
 
Adding Average Depth (available in Gauge mode) to literally any field in Single or Multi-gas mode is what I’d love. At the moment, you have to pick between diving in computer mode, or being able to access Average Depth for ratio deco on-the-fly.
I’m sad to say that it does not seem that avg depth is available in the configurable fields. The “dive fields” available seem to be the same as in the Mk2i - CNS, OTU, TTS, etc.

Frankly, I think this is crazy.
 
Good write up! I'm hopefully going to upgrade my MK2i here in the next few months, and I'm glad to see the screen looking a lot crisper.

Are there any real differences between the T1 and T2 transmitters? I already have 2x T1 transmitters, and I haven't really seen anything on Garmin's site explaining why one may be better than another
The biggest difference between the T1 and T2 is the ability to use the diver-to-diver messaging system, which I don’t see as being a useful feature, but maybe someone will prove me wrong.

You can also connect more T2 transmitters to one computer (8 max vs. 5 with the T1). Again, probably fairly useless except for the one or two instructors in this world who will actually buy 8 of these things. (See here for details: Garmin Dive Computer and SubWave Network Air Integration Transmitter Compatibility | Garmin Customer Support)

I will not be buying a T2. In fact, I may buy another T1 as I’m already seeing their prices drop. As I said in the review, the Mk2i/T1 combination worked flawlessly for me over 90 dives, so I’m not exactly aching to upgrade the transmitter.
 
https://www.shearwater.com/products/teric/

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