Which dive computer should I buy?

The answer will depend on a number of factors, including the type of person you are and the sort of diving you do.

This short discussion should help you decide.


The first thing to do is decide which type of computer you want. There are four main categories to choose from.

Wrist computer

A strong argument in favour of carrying your dive computer on your wrist is that you are more likely to look at it frequently, especially if you are used to wearing a watch in your surface life. The main disadvantage of a wrist unit is that you can forget to put it on before you jump in the water. It is also a relatively small item of equipment and can easily get mislaid on a busy dive boat. You need to have the discipline to keep it attached to your BCD during the diving day while you are not wearing it.

Wristwatch style computer

These are designed for you to wear even when you are not going diving. Along with strange sunburn patterns, your wristwatch computer makes you instantly recognisable as a scuba diver. And, as you wear it all day every day, you don’t have to worry about accidentally leaving it behind. The disadvantage, of course, is that it has a small screen, so the graphics are less clear and pronounced, the data displayed is minimal and it can look cluttered.

Console computer

A large screen is the major point in favour of console units. Graphics can be large and clear and more information can be displayed. Also, you are highly unlikely to leave your console computer on the boat when you jump in, as it is permanently (or at least semi-permanently) attached to your regulator. Your console computer sits on the end of your high-pressure hose and can swing around underwater and when your dive gear is moved around. This means it can easily get damaged or act as a wrecking ball on the reef as you swim by. This problem can be eliminated by attaching a stainless steel clip to it and keeping it secured to a D-ring at ALL times. There is also the danger that, as the computer is sitting at the end of the hose, you may forget it is there or at least look at it less frequently than if it was on your wrist.

Head Up Display (HUD)

This is a relatively new computer design option, at least as far as sport divers are concerned. The HUD is a tiny screen attached to the top of your mask and suspended in front of the lens. The technology acts to project your dive data into the water ahead of you. The display is remarkably unobtrusive yet very easy to access with just a glance.

A HUD style computer is the most expensive option, but it is such an effective and convenient way for a diver to monitor their dive status that, who knows, as the years pass and this technology becomes better, cheaper and more widely available, it may end up being the type of computer we all use.


So, having chosen the type of computer you prefer, you now need to consider the major features offered. Some may be more important than others. Some may be completely irrelevant to you.


The primary function of all dive computers is to measure pressure and time, factor this data into a pre-set mathematical model and tell you your decompression status. The pressure reading is translated into depth on your screen. Dive computer marketing often makes much of the software the computer uses, emphasising its safety. However, if you interpret “safe” as meaning “entirely free of risk”, then no dive computer can ever be considered “safe”. Although there are commonly accepted assumptions, the phenomenon of decompression illness is not completely understood. Divers still get “bent’ on dives when they follow their computers and stay well within no-decompression limits.

Decompression information may differ between computer brands because of different mathematical models or minor differences in the application of the chosen model. The good news is, however, that all dive computers on the market today operate within commonly accepted limits and no matter which brand you choose, you can be sure that you will not be buying a device that presents less or greater risk to your safety on a dive than another.

All of which is a long-winded way of saying that the algorithm is not a factor that should concern you greatly when you are making your choice. Nor should you be influenced by the fact that you can programme the computer with more than one gas. You can worry about this if and when you decide to get into technical diving.

However, if you are an older person, sometimes dive in chilly water or regularly do high-exertion dives involving long tiring swims, you might want to look for a dive computer that allows you to apply a conservative cushion to the decompression calculations.


It used to be the case that many divers preferred the convenience of a computer with a user-changeable battery to one that had to be returned to the manufacturer for service when the battery ran low. This was before the advent of efficient, durable rechargeable battery technology ushered in by the mobile phone era. Now, you can just plug your computer in at the end of the diving day and be confident that the battery will last for many years.

Of course, having a computer with a user-changeable battery does enable you to fix a low or dead battery issue just by carrying a spare. But, the downside of this has always been that, when you change the battery, you have to open the cap to the battery compartment. The cap has o-rings around it to keep the water out when it is closed, but careless hands can fail to seal the cap completely and o-rings can become worn, break, fall out or be compromised by a rogue hair or tear. The compartment then becomes a hole allowing water to gain access to the electronics. Just one drop will fry a computer forever. A rechargeable computer has no holes.


Air-integrated computers read your cylinder pressure from the high-pressure hose they are attached to or via signals received from an electronic sender plugged directly into your regulator first stage. More advanced models can use this information to give you a prediction of time remaining at depth taking into account your decompression status, breathing rate and residual cylinder pressure.

This is an excellent tool to have at your disposal, but don’t forget that all dive computers are battery-powered so they can fail during a dive. If a non-air-integrated computer fails, you lose your depth, time and decompression data. If an air-integrated computer fails, you lose your cylinder contents information too.

Having said this, of course, if your computer fails, you and your buddy should be making a direct ascent together and ending the dive, whatever type of unit you are using.


Diver interaction with most dive computers is via one, two or three buttons, pressed alone or in combination and / or with long or short pushes. On screen indicators guiding you through the process are useful and preferable, but designers find it hard to find space for these on smaller screens. The best advice is, once you have narrowed down your choice to two or three models, play with the display units in the dive shop to see which screen navigation system you personally find most intuitive.

It is true that, whichever you choose, you will eventually get used to it, but if, like many people, your work – life balance often creates large gaps between dive trips and you find yourself having to re-learn how to use your computer over and over again, then the process will be easier if you have chosen a model you find logical and comprehensive in the first place.


Computer manufacturers love alarms. They see alarms as protecting them from liability in the event that a diver comes to harm while using their product. You may love alarms too, but if you are not THAT enthusiastic about them, then you may look for a computer model that allows you to choose between audible and visual alarms for various contingencies or even whether to have an alarm at all for some things.


I hope this helps you find a pathway through the myriad alternatives out there. And, if, at the end of the process you ignore all this advice and choose a computer just because it looks cool or matches the colour of your wetsuit, then don’t worry. The main tasks of a dive computer are to tell you how long you have been down, how deep you are, how deep you have been and how slowly you have to come up to the surface with the minimum possible risk of decompression sickness – and they all do that. The rest is just frills.