It’s one of the more conservative dive computers on the market, but that conservative factor is customizable.

I used this computer simultaneously with another computer of a different make and model, and found that the Suunto D6i was only slightly more difficult to learn how to use, and that it beeped at me a little more frequently than the other computer. However, I’m sure that if I had spent more time configuring the alarms, this might not have happened. This computer is a powerhouse, and it’s worth the time to learn all it can do, and how to use it the way you want or need.

I wouldn’t recommend this computer to divers only interested in diving shallow reefs — though there’s no reason that such a diver couldn’t use it, this computer might be a little too much. The D6i is more suited to those interested in diving closer to recreational limits or deeper, using air mixes, learning navigation, or freediving.


The only big con that I found with this computer involved the freediving mode. The mode itself functions fine, with an apnea timer, depth alarms and surface-interval alarms. However, if you use this computer in free mode, you cannot use it in dive mode for 24 hours afterwards. It will still function in gauge mode, but that mode doesn’t do NDL calculations. If you’re not aware of this and decide to do some snorkeling or freediving prior to your dives using it in free-dive mode, then it’s a pretty significant issue. It is easily avoided though, as long as you’re aware.

Also, the battery is not user replaceable, and there’s no data retention during a battery swap. So before you send it in to get the battery changed, either download all of your dives or jot them down by hand.

Now for some technical details:

Air Mixes

The Suunto D6i will operate with air or nitrox up to 99 percent. It can record up to two nitrox mixes and it’s possible to switch mixes during dives. PO2. can be set from .5 – 1.6.

Dive-Mode Display

While in dive mode, using air, the computer face displays the current depth, your no-deco time remaining, ascent rate and air information, if you’re using the wireless transmitter. With just the touch of a button, you can also access the water temperature, time, your max depth and elapsed dive time. Using nitrox, you get all of the above plus the FO2 set point, current PO2, and O2 toxicity level expressed as a percentage. Display contrast and brightness can also be adjusted.

Deco Mode

You’ll trigger this mode if you exceed your NDL. It sets up a series of required deco stops and if you miss any of them, it will eventually revert to an error mode and will only operate as a gauge for the next 48 hours. The computer guides you through the deco stops by displaying your next required ‘ceiling’ depth and stop time. It even displays your total ‘ascent time to surface’ estimation if you make all of your required stops. After you make a required stop for the required time, the ceiling depth changes and the computer indicates that you should ascend to that depth. This continues until you reach the surface.


The digital compass must be calibrated prior to use. This should be done any time you have moved around different magnetic fields just to make sure it’s on target. You can enter compass mode any time prior to or during a dive. The handy thing about the Suunto compass is that it’s a tilt compass, so your wrist position doesn’t matter. You will get accurate readings whether you hold it out flat, or tilt it up to view it in a more natural position.


The computer has a few alarms available. The depth alarm can be set pre-dive and will alert you when you reach that depth. If you are using wireless-air integration, the tank pressure alarm will alert you when your tank pressure reaches a previously specified amount. The dive-time alarm can be set for anywhere between 1 and 999 minutes. There are also two freediving alarms, depth notification and surface interval. Both can be configured.


This computer will hold up to 80 dive hours in the detailed logbook. You can set the sampling rate to 10 to 60 seconds, meaning it records your depth that often. You can also use the bookmark feature to remind you of something cool you saw at a specific time or depth. By bookmarking it, you don’t have to remember your profile at that moment; the computer will do it for you. If you use the proprietary USB cable, you can connect to a computer and download all of this information into the DM4 software. It will graph your dive for you according to the sampling rate, showing you exactly how deep you were and when. If you’re using air integration, this information can be used to chart your air consumption. It also tells you if you ascended too quickly and the water temperature at each sampling point. It’s essentially a data dump of your entire dive.

Key points:

  • Operating modes — time, dive, plan, memory
  • Dive modes – air, nitrox, gauge, free-dive
  • Tilt compass
  • Wireless air integration — one transmitter
  • Algorithm — Suunto RGBM algorithm with continuous decompression calculations
  • Auto safety stop
  • Altitude adjustment
  • Logbook software

Final Notes

This computer has a lot going on and a lot going for it. That it’s conservative helps mitigate DCS risk, and because it’s so customizable you can match it up with just about any diver, as long as you take the time to learn how to operate it. Read the manual; play with the computer; learn the modes and the alarms, and set it up to match your diving style. By taking that extra time you will get much more out of this computer and be a happier, safer diver for it.