There are many items of equipment you need to have when diving, and some come naturally when you are investing in your kit. Have you, however, got a dive computer? If not you really need to take a look at these very clever and versatile – and indeed potentially life-saving – items, as they really are an important part of any diver’s regular gear.
What’s a dive computer? You likely know this already so we’ll keep it short: a dive computer is a device that usually worn on the wrist, and generally about the size of your sports watches.
It’s designed and equipped to give you vital information – such as the depth you are at, your ascent rate, and decompression stops – and as such is a safety precaution of the highest order. This is why it’s really important to understand how to care for your dive computer too.
Five Reasons Why You Need a Dive Computer
The whole point of a dive computer is to make your life as a diver easier. It’s worth knowing that some come with features that others do not – you will find some, for example, that don’t have a compass included – and there is a wide gulf in prices across the various models available.
We’re not going into details of individual dive computers and the best dive computer reviews in this article; what we are going to do is give you five good reasons why you need one. That’s not to say there are only five, as when you start reading what a dive computer can do for you, then you’ll see other benefits too.
1. Safety First
Safety is a priority in all walks of life, yet for divers, even the slightest lapse in attention to safety procedures can be very dangerous, and even fatal. You can, of course, plan your dive and calculate, for example, your decompression manually, and many experienced divers have grown up with this method and still carry it out.
Yet, even the most knowledgeable can make mistakes, but a dive computer will give you a true plan that you can rely upon. Also, features such as air integration – which will calculate how much gas you have left – make the dive computer a must-have device, and there’s more.
2. Accuracy
This advice follows that above in many ways. You may be the most experienced diver of all time with full knowledge of how to plan everything involved, yet the tiniest of errors in your calculations can make a lot of difference and can be a danger to your safety. 
A dive computer will track everything it needs to in terms of how long you’ve been under the water, with complete and unrivaled accuracy.
This cannot be guaranteed with manual planning, so you are assured as much time diving as is safely possible.
Some dive computers, like the Suunto Eon Steel computer, will give you accurate readings of the air you have left, the depth you are at and even the exact time, so you can rely upon it to give you the right information, at the right time.
3. Ascent Rate Monitor
For many people, an ascent rate monitor may be the most important reason to buy a dive computer. Every diver – and even non-divers – knows the dangers of coming up too quickly, and every diver does all they can to keep within the safe limits.
However, it’s not always possible to know how far you are ascending without help, and you can easily miscalculate – that old ‘human error’ element makes its way into things again!
A dive computer will accurately monitor your ascent speed; rather than you relying on age-old methods that have been used in the past, it will give you an entirely accurate and constant reading of your ascent speed.
Also, if you get above a certain rate – usually 10m/minute – it will sound an alarm and tell you to slow down. Go beyond 12m/minute and it will tell you to stop. Some dive computers also have a lock-out function so you can’t dive for a given time if you have exceeded the safe limits.
There really is no exaggerating just how important this feature is on a dive computer; without it, you are left to make assumptions that could result in serious injury or fatality.
4. Dive Logs
One of the great functions of a dive computer is that of being able to log your dives and record them.
This means that you don’t have to rely on memory alone to log all the details of your dive, as you always want and need to do because the little computer on your wrist will do it all for you.
And by that we mean all; it will log everything about your dive that you need it to, in more detail than you could manually, and with software downloaded you simply transfer it all onto your home computer. It’s a great way of saving time and effort. The Mares Smart Wrist dive computer, for example, can log up to It can log 25 hours of dives, and even has a dive plan mode.
5. Dive Nitrox
With a dive computer, you can accurately calculate your Nitrox mix, and it is far easier, quicker and more accurate than doing it manually. You should, however, check and analyze your gas before diving – this is a basic rule whether you’re using a dive computer or not – but with the machine, you simply add in your mix, and you’re ready to go.
As we said in our introduction, these are not the only five functions that a dive computer offers you. Some come with many more customizable details, and they are very capable indeed.
What we have listed here are the basics required of any dive computer, whether for beginners or experienced users, and you will find that most of the models on the market provide all of them, and more. What you may find missing is a compass, and some do not have air integration capability.
Look for the dive computer that is the right size and price for you – keep an eye on cost as it can vary considerably – and you will find one that suits your requirements.
Finally, always remember that there is scope for human error even when programming a dive computer, so ensure you check all your measurements and inputs carefully before you commence your dive.
