Features
Standard Features
All of the standard features you'd expect are here. This computer will log depth, dive time, temperature, and no-decompression limits over multiple dives as well as working with air and nitrox. The Suunto D9 acts as a watch when you're not underwater and can also be used in gauge and freediving modes, can be switched between Metric and Imperial, and can be adjusted for altitude diving.
Air Integration
Using the optional Suunto Wireless Transmitter, which connects directly to the first-stage regulator, this computer can also act as a SPG. Multiple transmitters can be used to monitor the pressure of more than one tank which is quite handy for technical divers and for instructors who might want to monitors their student's air consumption. I found the wireless transmitter easy to use and the only problem comes when you forget to activate it before the dive. If this happens, and you're not equipped with an additional SPG you need to return to the surface to activate it. Over hundreds of dives I've never had a problem with reliability.
Multiple-Gas Mixes
The Suunto D9 can handle up the three different gas mixes containing 21-100% oxygen and even allows you to switch gases during the dive. This feature makes the Suunto D9 particularly attractive to deep and technical divers.
Deep Stop Option
With decompression calculations based on Suunto's Deep Stop RGBM you have the option of making additional deep stops or traditional safety stops which adds extra safety. The Suunto D9 can also be used to depths of 660 feet (200 meters) for those wanting to go really deep.
Digital Compass
One thing that sets the Suunto D9 apart from most of its competitors is its fantastic built in digital compass. With a graphical compass rose, an exact bearing display, and the ability to store multiple headings I've found the compass easy to use and superior to a traditional compass. The ability to store headings in memory is particularly useful when carrying out mapping tasks.
Dive Logging
The Suunto D9 comes with a USB interface and PC software to allow for dives to be easily logged. The dive logs are a real treat, showing a complete dive profile that you can click on to see all of the data at any point during the dive. You can also store a huge variety of extra information about the dive site, conditions, equipment, notes, and even photos from the dive. The only drawback is that the software is not available for Mac.
Conclusion
The Suunto D9 contains the complete package of dive gauges all in one small stylish wristwatch-sized computer. The only major inconvenience with the Suunto D9 is the need to return it to a service center in order to replace the expensive proprietary battery. However, with an easy to use interface and fantastic dive logging software, the Suunto D9 really is the king of recreational dive computers.
