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Suunto Cobra 3 - Find Your Precise Destination Underwater

Suunto Cobra 3 - Find Your Precise Destination Underwater

Suunto Cobra 3 is hose air-integrated dive computer. Ideal for serious beginners and advanced divers. Has integrated digital compass, Altitude and Personal Conservative Factor adjustment and RGBM attenuation function, 2 Nitrox gas mixes and switching gases during a dive.

General Information
User Interface
Your Review



Suunto Cobra 3 was introduced to the scubadiving market as a further development of well-known hose air-integrated dive computer Suunto Cobra. New version can be used for variety of diving conditions and it can be recommended dive computer for beginners and advanced divers.

Cobra 3 is a step up in development of hose air-integrated Suunto dive computers. It got many new and distinctive features from its predecessor Suunto Cobra.


We will describe many functions of Cobra 3 later in our review, but now let's point out some differences of how this dive computer is dissimilar to Cobra.

Below is a list of features we can find in Suunto Cobra 3 dive computer and overall we got completely new dive equipment:

  1. Redesigned user interface – Cobra 3 has 4 operating buttons vs. 3 buttons in Cobra;
  2. Different display layout – 2 bar graphs: Tank Pressure and Ascent Rate;
  3. Integrated digital compass;
  4. Different structure of the main operation modes and therefore different menu structure;
  5. 2 Nitrox gas mixes vs. 1 Nitrox gas mix in Cobra;
  6. Gas change during a dive;
  7. Deep Stops option – ON/OFF;
  8. RGBM attenuation option;
  9. Memory capacity – 42 hours with 20 seconds sampling rate vs. 36 hours with 20 seconds sampling rate in Cobra


Suunto Cobra 3 Features CardCopy this Suunto Cobra 3 Features & Alarms Card for your Reference and Share with your friends and buddies! 



Benefits of using Suunto Cobra 3 dive computer

  • you will get Nitrox capable hose air-integrated dive computer with easy set up for recreational and technical diving with double Nitrox mix support;
  • you will get highly adjustable instrument;
  • you will be aware of your air consumption all the time thanks to hose air integration of Suunto Cobra 3 dive computer;
  • you will find your way underwater with ease thanks to integrated digital compass;
  • you will be able to replace a battery yourself with ease








User Interface
4 buttons
Dive Modes
Air, Nitrox, Gauge
Integrated Digital Compass
Suunto RGBM
Number of Gas Mixes
Air, 21% - 99%
0.5 - 1.6 bar
Air Integration
Safety Stop (SS)
Deep Stop (DS)
Conservative Factor
Altitude adjustment
A0/A1/A2 (range from 0 to 3000 meters)
Gas Switching
Dive Planner
9 - 45 meters
Logbook Capacity
42 hrs with 20 sec sampling rate
Max Operational Depth
100 meters
Backlight duration
OFF/5/10/20/30/60 sec
Sampling Rate
1/10/20/30/60 sec
User Replaceable Battery
Data Retention or battery 'hot swap'
PC Interface
2 years










Suunto Cobra 3 has 4 operating buttons on the user interface: MODE, SELECT, UP, DOWN. I reckon that Suunto, by redesigning user’s interface, made its dive computer more intuitive and easier to understand - I felt that Cobra 3 became really user friendly when setting and diving with it.

This dive computer has only 2 bar graphs:

  1. Tank Pressure Bar Graph;
  2. Ascent Rate Bar Graph


These names speak for themselves, so we, probably, don’t need to discuss how they work – it’s understandably!

During a dive or on surface we have access to few displays – main and alternatives, with data according to mode you are in. To swap between them – use UP/DOWN buttons, and Cobra 3 will display additional information – that’s pretty straightforward too.







One of four main operating modes of Suunto Cobra 3 is Time mode. And before setting parameters for Dive Mode we are going to adjust following parameters for Time Mode from the beginning:

  • daily alarm;
  • time;
  • date;
  • units;
  • backlight – you may set it to ON/OFF or adjust for 5/10/20/30/60 seconds;
  • tones


After setting Time parameters we need to level and tilt calibrate our digital compass. I found that it was easy task and compass picked up all adjustments pretty fast (just a few attempts). Digital Compass may be activated in Time and Dive modes only by pressing and holding SELECT button.

It is worth to mention that you should not use Cobra 3 with another dive compass in pair! Because digital compass is very sensitive to magnet inside other compass and if you hold Cobra and other dive compass close together – all the readings will be wrong!


Next, we came up to more exciting task – setting up parameters for diving with Air and Nitrox!

From the Dive mode we are able to adjust variety of settings and each dive sub-mode (Air, Nitrox, and Gauge) has its own parameters that are accessible only from particular sub-mode. For example, you may set FO2 and PO2 values only from Nitrox sub-mode, but not from Air or Gauge.

So, let’s get started setting our Suunto Cobra 3! All parameters are listed below:

  • Depth alarm – factory preset to 30 meters; user adjustable at 3 – 100 meters range;
  • Dive Time alarm – user adjustable at 1 – 999 minutes range;
  • FO2 Mix 1 – Air, 21% - 99%;
  • FO2 Mix 2 – OFF, 21% - 99%;
  • PO2 – factory default 1.4 bar; user adjustable 0.5 – 1.6 bar;
  • Altitude Program setting: A0(0 – 300 meters)/A1(300 – 1500 meters)/A2(1500 – 3000 meters);
  • Personal Conservative Factor setting: P0/P1/P2 – to make this dive computer progressively more conservative;
  • Sampling rate – factory default 20 seconds; user adjustable 1/10/20/30/60 seconds;
  • Deep Stop – ON/OFF; if Deep Stop is set to OFF, only Safety Stops prompts will be displayed; if Deep Stop is set to ON – you may adjust duration for 1 or 2 minutes;
  • RGBM attenuation – 100% or 50%;
  • Units;
  • Tank Pressure alarm – can be set to ON/OFF or at the range 10 – 200 bar and it is a secondary alarm point; first alarm point is 50 bar and it is factory preset, fixed, and can not be changed – this is done to our safety


If we compare this set of options with Cobra – it is noticeable how Suunto redesigned approach to programming and customizing this dive computer by expanding list of features and adding new ones.

After setting all of these parameters we are ready to go to our underwater adventure with Suunto Cobra 3 dive computer and explore its behavioural habits in reality!

Before actually going into the water it is good practice to activate Dive mode, because dive computer needs to do pre-checks and it will display some settings that you adjusted before, battery and display status, nitrox settings (if set for Nitrox), etc.







Suunto Cobra 3: Diving With Air & Nitrox

Reading data wouldn’t make any difficulties – all values are sharp and clear (to see clearly digits that are located close to the display protector edge I had to hold Cobra 3 at the certain angle), backlight is strong, and when you know display layout and what it shows during different modes – just glance down and you will grasp quick and easy all information.


Suunto Cobra 3 NO-DECO Card

Copy this Suunto Cobra 3 NO-DECO Card for your Reference and Share with your friends and buddies!


It may show you Diver Attention symbol if you need to extend surface time.

Suunto Cobra 3, like other dive computers from Suunto, has Bookmark function. You may store data of your dive profile in memory by pressing SELECT button. After that you will be able to download to PC for viewing and examining you dive profile.

Cobra 3 continuously monitors your air consumption and will warn you by audio when tank pressure will drop to 50 bar. This kind of alarm is factory fixed for our safety and can not be changed or set to OFF.

Dive computer warns us when Air Time becomes ‘zero’, but even in this case we still have safe reserve of air with 35 bar pressure.

If you hear this beeps and see corresponding values of those two alarms we just discussed – it’s time to ascend, buddy!


And to manage the ascent – Suunto Cobra 3 dive computer has Ascent Rate Bar Graph. It works as a speedometer – if you ascend slowly – fewer segments are displayed, if you ascend faster – more segments are displayed.

In certain moment you may get Ascent Rate alarm. It will happen if you exceed maximum allowable ascent rate and in this case Mandatory Safety Stop will be prompted with all corresponding notations, ceiling depth and stop time when you reach certain depth zone.


After every dive below 10 meters – Suunto Cobra 3 prompts us to make a Recommended Safety Stop for 3 minutes. You may miss it without penalty, but I prefer stop and enjoy the view before going out of the water (mainly I do stops just to be on the safe side!)

Mandatory Safety Stop is compulsory. If you miss this one – you will get shorter No-Decompression times during next dive and you need to stay longer on surface before the next dive.


When we set our Suunto Cobra 3 for Nitrox dive – we must enter exact numbers of FO2 and PO2. After we did that – dive computer would calculate maximum operational depth (MOD) according to FO2 and PO2.

Suunto Cobra 3 allows us to set 2 Nitrox gas mixes with FO2 – 21% - 99% and PO2 0.5 – 1.6 bar.

During Nitrox dive we have similar data on the display like in Air dive, but with few additions that are specific to Nitrox mode:

  • FO2 and PO2 values;
  • Oxygen Limit Fraction (OLF) – oxygen toxicity level


As Cobra 3 allows us to set 2 Nitrox gas mixes – it allows us to change them during a dive too, if we set MIX 2 to ON.

And this is a very simple procedure – just press and hold UP button till you see appropriate display and then by using UP or DOWN buttons we select desirable gas mix; after that – press button SELECT, and dive computer sets the mix that you selected and will start all calculations according to the settings of this gas mix.

If PO2 limit of the selected gas mix was exceeded – Suunto Cobra 3 wouldn’t allow you to change to that gas mix. It will be shown, but you couldn’t pick it up for selection.


If you exceed your No-Decompression Limits (NDLs) – your No-Decompression time obviously becomes ‘zero’. And at that moment Suunto Cobra 3 activates Decompression mode. All data that you will get after that is related to this mode. During decompression you will be prompted to complete one or few decompression stops at a range of depths.

Cobra 3, as well as other Suunto dive computers, has Continuous Decompression feature that allows us to perform decompression within the certain range of depths, named Decompression range. It starts from the ‘floor’ (deepest depth where deco stop time won’t increase) to the ‘ceiling’ (shallowest depth) and decompression is done between them.

Cobra 3 manages decompression precisely by displaying following data:

  • guiding arrows (for your correct ceiling depth);
  • Ascent Time in minutes (total time to surface, including time to reach the correct ceiling, time to stop at the ceiling, Mandatory Safety Stop (if any), time to surface after ceiling);
  • Ceiling depth;
  • Dive time;
  • max depth reached during a dive;
  • tank pressure value and Tank Pressure Bar Graph, etc.


If you ascended above correct decompression ceiling, dive computer would give you an audio alarm with corresponding icons, your current depth and ceiling depth values, and Error mark. It means that you have only 3 minutes to correct you position and go deeper to ceiling depth displayed or a bit below.

If you violate the decompression – Suunto Cobra 3 will activate permanent Error Mode and will work as a depth gauge and timer only. You must not dive for at least 48 hours then!


Suunto Cobra 3: Diving In GAUGE Mode

In this mode dive computer doesn’t calculate no-decompression limits for us and it doesn’t monitor the ascent rate either. It works as a depth gauge and timer only.

Display looks not as rich with data as in other dive modes and shows us following information:

  1. tank pressure value and Bar Graph;
  2. current depth;
  3. Elapsed Dive Time (EDT);
  4. Dive Timer in the center of the display


If you set Bookmark – Suunto Cobra 3 will display notation about storing it in dive profile memory. The only inconvenience I found in dive computer operation during Gauge mode was using the same button – SELECT to create a bookmark and reset Dive Timer to use it as a stopwatch.

Somehow I ‘managed’ to create few bookmarks, which, actually, I didn’t want to make, instead of resetting Timer. Maybe it was an issue only with my unit? Would be nice to have some response from you, guys, about this thing!

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Suunto Cobra 3 has two modes that allow you to plan and simulate your dives, view logs and history of your dives and download dive profiles to PC using special software and data cable. These two modes are:

  1. Plan mode with Dive Planner and Dive Simulator sub-modes;
  2. Memory mode with Logbook and History of your dives


Dive Planner is function that allows us to go through No-Decompression limits according to nitrogen and oxygen accumulation from previous dives (if any) – useful feature for planning your following dives.

Dive Simulator helps user to get to know dive computer and learn it faster by performing ‘virtual’ dive by entering dive data and manipulating buttons for ascent and descent. Dive computer will show you displays with appropriate information, warnings and alarms - all like in real dive.

Logbook has 3 pages, it is very detailed and may store approximately 42 dive hours with 20 seconds sampling rate. Capacity of the memory depends on the sampling rate and we can adjust it at the range 1/10/20/30/60 seconds.


History is a summary of all your dives. It stores information of 999 dives and 999 diving hours and shows the maximum depth reached, total number of dives, and total accumulated dive hours.

Suunto Cobra 3 dive computer has optional software Suunto Dive Manager (SDM) to transfer your dive logs to PC, using data cable. After we did that – we may organize our dive history, view profiles, print them, share with friends, and maybe even boast about our diving achievements!

SDM and data cable cost about USD$ 70 – 80, so I think it is nice thing to have in hand! It will add flexibility and more freedom of using Cobra 3 – you won’t worry anymore about your old logs – they can easily be downloaded to PC!







Suunto Cobra 3: What Divers Say


  • extremely easy to use, as long as you actually read the instruction manual;
  • excellent integrated digital compass feature;
  • on-unit dive simulator is a great feature;
  • perfect for recreational diver and may be recommended dive computer for the very beginner;
  • easy manages Decompression mode



  • conservative dive computer;
  • manufacturer support not very good;
  • no battery 'hot swap' feature;
  • software and PC interface cable are optional


Cobra 3 is greatly improved since Suunto Cobra and it gains few brand-new features, like new user interface, integrated digital compass, double nitrox gas mix feature, FO2 settings, and gas changing.

From my experience – Suunto Cobra 3 is easy to use dive computer and it comes when you study manuals. Just devote some time – it is easy written and easy to understand.


I found only two minor things that are worth to tell about – compass calibration and viewing digits that are located close to the edge of display protector.
Compass got calibrated after few attempts – it is not a problem. Looks like this is not only little issue of Suunto models of dive computers – other brands didn’t get calibrated from the first attempt as well!

And second issue - viewing smaller digits that are closer to the edge of display protector – may be resolved by placing Cobra 3 at certain angle.

Other than that – Suunto Cobra 3 is a perfect addition to Suunto family of the dive computers!


Suunto Cobra 3 dive computer

Suunto Cobra 3

Dive-Computer-Wizard Rating
golden star golden star golden star golden star half star


So, if you are a beginner who is growing in diving career or experienced recreational diver, who wants to upgrade from previous models or maybe just to have a reliable backup and want to have hose air-integrated dive computer - Suunto Cobra 3 is definitely requires your attention!



Add comment
Jake, 5 November 2013 03:57
Easy To Learn Advanced Dive Computer

I selected Suunto Cobra 3 over Oceanic Pro Plus because of it was easier to comprehend user manual and better users' reviews. As I'm and advanced diver, I often use compass and double gas capabilities would be very handy feature!

I learnt and got used to Cobra 3 quite quick, even it has comprehensive number of functions, thanks to easy to understand user manual and dive computer iterface. Setting the dive computer and using it underwater - an easy task. And it looks more solid built over Aeris or Oceanic models with hose air integration.

Colin, 6 April 2013 10:35
Suunto Cobra 3 - Top Recreational Hose Air-Integrated Dive Computer

I've logged more than 350 dives on my Suunto Cobra 3. Dive computer has fully user customizable number of functions, but user manual that comes with it makes all set up process very easy. I love its big viewing area with lots of essential dive data displayed, that is easy to read and intuitive.

Double gas mix and integrated compass - are nice and handy additions to the whole setup!

Price is a bit high, but it does not make it less affordable, if someone prefers reliability and solid design!

Walter, 22 September 2011 08:01
Suunto Cobra 3 - Great Dive Computer But Very Conservative

I am recreational diver and once decided to upgrade my Suunto Cobra with Cobra 3. This dive computer has everything that could recreational diver want: lots of functions, 2 Nitrox mixes, digital compass.

User manual wasn't confusing for me and I learnt it fast. Compass calibration went rather smoothly. After reading some reviews, I expected that I might have problems with it - but, no. And underwater compass behaves very well!

Cobra 3 has good contrast display, only one inconvenience, that some digits (dive time and tank pressure) located near the edge of the protective plastic shield and they are small, so it is difficult to see them under certain angles.

Also about conservative times - Cobra 3 is quite conservative even without setting Personal Conservative Factor. So if you want longer bottom times - you need to shop around for more liberal dive computer. But I am comfortable with it - I always want to stay on the safe side.

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