Dirk’s Dive Computer Ramblings

Dirk’s Dive Computer Ramblings

What am I looking for?

A lot of people ask me for dive computer recommendations. And of course the first thing to keep in mind here is the questions “what are you looking for?”. What’s your budget. How much do you dive? What type of diving do you do? What are the “must have” features for you?

So I’ll start for answering these question for me. While I am tech certified I rarely go on tech dives. The vast majority of my diving is warm water recreational diving, ususally with a camera in my hands. I dive a fair bit for someone who doesn’t have a good dive site minutes from their house. In the eight years that I have been certified I got to nearly 600 dives. So any investment in dive computers gets ammortized over a decent number of dives (and, full disclosure -- many of the dive computers I have are loaners from dive computer manufacturers). Must have features for me are (in this order):

  • gas integration, preferably hoseless
  • bright, easy to read color screen
  • well designed visualization of the most important information
  • decent battery life

With that out of the way, here are my thoughts on some of the computers I currently dive with (or used in the past).


Teric and Perdix AI

I have to start with Shearwater, since right now (beginning of 2019), they are at the top for both being the best company to work with as a developer (maybe matched by Heinrichs Weikamp), and also making my two top choices for dive computers, the Teric (better choice for warm water) and the Perdix AI (likely the better choice for cold water).
The displays are fantastic. The way data is presented and the ability to configure that presentation is best in class. The user interactions through the buttons is fine on the Perdix AI (two buttons) and outstanding on the Teric (four buttons). In hundreds of dives I have never been confused about the data my Shearwater dive computer has shown me. I’ve never had one fail on me. All the things that I want from a dive computer these do. And then there is the interaction with Shearwater. They have been absolutely amazing in the quality of the documentation of their download protocol and in their willingness to support the Subsurface developers. They answer questions, they listen to feedback. You can tell, I’m excited.

If there’s one thing I regret about these dive computers is that they only support BLE as download protocol. Which is often a pain to set up (espcicially for Windows users) and which regarless of platform is really, really slow. Downloading a larger set of dives can take a significant amount of time -- even just downloading five dives at the end of a long dive takes quite a while. But hey, given everything else, I’m willing to deal with that.

Shearwater has quite a few older dive computers. They were solid tech dive computers, but they all lacked gas integration. So while I’ve used them for many years, they never managed to make it to the top of my list.


EON Steel (and EON Core)

I don’t have an EON Core -- Linus has that one. I dive an EON Steel but from a display / UI / functionality perspective the two are very very similar.

When I first got the EON Steel, my impressions wasn’t all that great. It’s big, klunky and heavy. The bungy cords don’t work well, I end up using the more traditional wrist strap because it’s so heavy that it keeps sliding with the bungy cords. But once I started diving the EON Steel I quickly learned to really like it. It’s still a dive computer I’d recommend. Here’s why:

The display is good (and the latest firmware updates have made improvements to the layout). The new transmitter so far hasn’t given me problems (the old Suunto transmitters had many issues) and given that you explicitly pair it based on an ID I think Suunto has a solid solution. The default UI is fine and reasonably intuitive to use even when slightly narked. But even better, you can create your own UI (within reason) and really get the elements at your finger tips that you care about while diving. The compass seems very responsive and can be viewed in parallel with important key information during the dive.
It’s hard for me to recommend a Suunto device. Suunto’s unwillingness to work with the Subsurface and libdivecomputer developers is a big issue for me. Other vendors are making things so much easier for us. So why would I recommend a dive computer from a vendor that’s such a pain? Because the combination of a wrist computer with hose-less air integration, active display that is easy to read both on the surface and (most importantly) under water, that is configurable and that has a download model that we were able to reverse engineer so that we have pretty complete support for it… the EON Steel simply hits the mark in all the categories that I care about.
USB download is very fast. BLE download from Android or iOS is supported in Subsurface, but SLOW. Still, it’s nice and easy and especially if all you want to do is download the last couple of dives, it doesn’t take too long.

Older Suunto dive computers

I started out with a Suunto Gecko -- more specifically, Linus’ Suunto Gecko… until a friend of ours lost it…

The Gecko and the pretty much identical Zoop are very commonly used by beginners. The user interface is not the worst ever (those honors are fought over by the single button computers from many vendors -- do not get a single button dive computer…). The passive display is hard to read in the best circumstances and don’t try to use it in bad visibility or during a night dive. Yes, you can shine a light on it and it will glow for a short time… but no, that’s not a solution (but at least it’s better than the button controlled light on other passive display and Suuntos like the Vyper Air, I guess). Fundamentally I really don’t want a passive display under water. And I really like air integration. So the Gecko / Zoop are pretty close to the bottom of my list.

Atomics Aquatics Cobalt 2

If I wasn’t so adamant about wanting a wrist mounted dive computer, this would be the obvious recommendation. Great display. Great UI. The best compass I’ve seen in a dive computer. Intuitive to use under water. Great buttons. Incredibly fast (and reliable) download to Subsurface. An excellent dive computer.

The company that actually designs the Cobalt (and then licenses it to Atomics Aquatics) has been a pleasure to work with. Very smart people, very willing to help Subsurface and libdivecomputer developers, very interested in doing things right.
It’s a rock solid choice. If you are OK with a hose based console the Cobalt 2 would be near the top of my list.

Uemis Zurich SDA

I bought this for a boat load of money literally three weeks before the original Uemis went into bankruptcy. I ended up writing the downloader and parser for it as the original Uemis had this idiotic idea of creating a captive portal for their customers which would be the only place you could keep your dive data. No import into other software, no export from the portal. And let’s just say it right here… that download algorithm? Calling it a stupid pile of crud is about the nicest I can come up with… they have a full fledged USB interface… there would have been so many good ways to implement this. They had to try really, really hard to make it suck so bad. It’s slow, unreliable, if you have a ton of dives and download for the first time the SDA runs out of space and you have to unplug and replug it to continue. I could go on. I also had the display fail on my first unit.

Having read this you’d assume that I hate this dive computer, right? Turns out it’s been my main dive computer for four years (before it finally got displaced by the Suunto EON Steel). I love the display and the UI; not the data entry on land -- that’s horrible… but I really like the experience during a dive. At any point in time I can see what is important. And they do a really good job of conveying information with color. Green: everything’s fine. Yellow: start paying attention. Red: this is important!

The buttons are extremely functional, even with thick gloves. The little solar panel means that on trips I never really think about charging it. The tank pressure transmitter has been rock solid for me.

I used to recommend this one. But given that there has been no innovation and no new product in more than six years and given that I know for a fact that the display that is used in the SDA is no longer made and that therefore they will run into parts supply issues very soon, I don’t think I can recommend the Uemis SDA anymore. Additionally, I have seen several of these fail. Either just stop taking a charge, or having the pressure sensor fail and suddenly your SDA thinks you are 130m deep, or other random issues, including damages to the internal data bases which prevent downloading. So no, don’t get this one.

Heinrichs & Weikamp

When talking about dive computers I love I immediately have to talk about the OSTC. I have several of their models OSTC2, OSTC3 and the OSTC Sport. I love the displays. I really like the UI. It always shows me what I want to know. You can even define a new gas during a dive (say your buddy dives a different gas and you run out for some reason but still have deco obligation… hopefully not a common scenario, but if it ever happens to you this might literally be a life saver). The size is great (especially OSTC3 and OSTC Sport). I like the bungee bands they use to hold it. Works extremely well on a 3mm and just as well on a dry suit.

As mentioned above, Heinrichs & Weikamp is one of the best company to work with (from a Subsurface perspective). They actively reach out to help us. They support the students working on Subsurface as part of the Google Summer of Code. They get open source. They get divers. They just get it.

The products are mostly geared towards tech divers. The UI is maybe a little more complex and because of the smaller size sometimes harder to read than for example the Suunto EON Steele, but I find it very to use and easy to get used to. The display is beautiful. If only they had an air integrated dive computer.

There are a few downsides. They aren’t available in the US, they are mainly available in Europe. And I had quite a few of these computers fail on me. Caveat: I got these as loaners, they were usually pre-release models, so this may be an overly harsh statement -- but having a dive computer fail on a trip for people who don’t typically have three or more dive computers with them… not so great.


I have used both the hose based Puck Air and the Icon HD Net Ready.

The hose based Puck Air has been my backup computer for a couple of years. I mostly used it as a bottom timer + SPG. The user interface with the single button is so horrible that I didn’t bother entering the correct gas that I was diving (which really doesn’t make it a good backup computer, does it?). The passive display is hard to read both on a dive boat and under water. Even worse than the old Suuntos. Frankly, it’s so bad that when recently I noticed that its battery was dead I didn’t even bother getting a new one. It’s just not a dive computer that I consider a reasonable choice.

The Icon HD Net Ready on the other hand looked close to what I wanted when it first came out. It has an active display. The UI is ugly (admittedly a matter of taste) but functional. I didn’t have as many problems as Linus did with reflections, but I agree that it can be an issue. What really bugs me about the Icon HD is that its battery life is just terrible. It burns through battery even when not in use so I always need to remember to recharge it the day before I go diving. And on a dive trip with five dives a day I tend to be at or around 10% battery during the last dive -- not encouraging. So if you don’t do five dives a day and if you don’t mind the huge size and the odd UI… it’s not a terrible choice, but there are so many better choices available. I haven’t tried the newer Mares dive computers, but what I’ve seen when talking to other divers on dive boats, none of them come close to what you get from one of the top choices mentioned earlier.


I’ve used the Datamask on a couple of dives. I found it actually not intuitive and far less seamless than looking at a wrist computer. And I had serious issues both with the tank pressure sensor and with downloading data from the mask. I’ve seen a few of their other models and none seemed even remotely comparable to what I currently am diving with.


This one is complicated. I absolutely love my Garmin Descent Mk1. As a fitness watch, and as a GPS tracker when diving. As a dive computer… It’s quite obviously a first try from a company that knows a lot about fitness watches and especially running watches and absolutely nothing about dive computers. Things like “NDL display with second precision” -- i.e. a display that states “34:27” for your NDL. And of course every second that number changes, often very wildly. Actually, so widely, that it’s at times distracting and useless. Overall the way information is presented during the dive is poor. There is no focus on the most important information (depth, NDL, dive time) and of course the dive computer isn’t gas integrated, so you don’t have your tank pressure, anyway. I’m sure that Garmin will continue to improve it (they have been good with firmware updates) and I am hopeful that they’ll come out with a successor that is gas integrated. I guess I can recommend this one as backup computer if you (like me) like to track the GPS location of your dives, but use another dive computer as the main dive computer which you check during a dive.