Suunto D4 is a full-deco wrist-watch dive computer.

It can operate up to a maximum depth of 100 meters. In addition to the traditional functions of a dive computer, D4 also includes a stopwatch, daily alarm, calendar and clock. You can find Suunto D4 for an average price of $ 500. Now, let's look in more details at some of the other functions offered by Suunto D4.

Suunto D4 is designed to provide highly accurate depth measurements. The computer records the depth three times a second. Suunto D4 takes into account the surface time and has a depth alarm. Apart from the sound alarm it has a visual alarm, giving you an exact indication when you should start your ascent. I like the fact that the watch is equipped with an electroluminescent backlight and thanks to the bright images of the numbers (dot-matrix display) the data is easy to read in any conditions.

Suunto D4 has four operational modes - Air, Nitrox, Free Dive and clock. In operation modes Air and Nitrox, the display shows current depth, maximum depth, diving time, remaining non-deco time and temperature. In Nitrox mode, you can adjust the oxygen content of your gas between 21% and 50%. You can also adjust the PO2 limit (partial pressure) between 0.5 and 1.6 bars, so you can spend more time underwater. You can check the ascending speed in both of the modes and if you exceed the desirable limits D4 will tell you so (visually on the display and with the sound alarm). Once you reach a depth of 6 m and 3 m the display will tell you the safety and deco stop times.

Suunto D4 uses the Suunto RGBM algorithm for decompression calculations. The Deep Stop function gives you additional information for your safety if you plan a diving at a greater depth.

Suunto D4 has a built-in diving simulator that will show you how long you can stay at a particular depth without having to make a decompression stop. All you need to do is to enter your planned maximum diving depth.

Suunto D4 also has a battery status indicator, which will warn you when the battery will exhaust. The battery is designed to last three to four years. In the event of a low battery indication, you must send your computer to an authorised dealer for a battery replacement.

Another great feature of D4 is the logbook, which stores your dive data and you can easily view the full profiles of your previous dives. Suunto D4 is also compatible with the optional Suunto Dive manager PC software, which provides more in-depth analysis and graphical representation of all your dives.