Beginners Guide to Buying A Dive Computer


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Odds are you’re reading this because you or someone you love recently learned to scuba dive and/or want more of it in your life (GREAT WHITE choice!).You’ve talked to diving professionals, read online blogs, similar to, but not as fishtastic as this one, for suggestions on what your first piece of dive gear should be. Did they all say a dive computer??

If they didn’t…

8 GREAT WHITE Reasons You Should Own A Dive Computer

Buying a dive computer can be overwhelming. There is a wide range of options from entry-level to technically advanced and lots of unfamiliar terms. That’s why we’ve put together a short guide that breaks down must knows behind a dive computer.

Entry-Level Dive Computer

Entry-level dive computers are simply called that because they are designed for beginners or recreational divers that don’t need all the bells and whistles of an advanced model.

As a new diver, you already have lots to learn and there is no reason to focus on features you don’t need yet. You still have lots of gear to buy, so if budget is an issue, consider a lower priced computer. However, keep in mind you still want one that is durable and will last for many years. 

Entry-level computers tend to have clear easy-to-read displays and are simple to learn. What’s more, when you decide to upgrade, they will be great back-up computers!

Dive Computer Algorithms

Dive computer algorithms vary between computers and manufacturers. An algorithm is a set of mathematical formulas that calculates safe diving limits. They use real-time measurements, such as depth, time at that depth, water temperature, ascent rate  etc. to do so. More simply put, it estimates how much gas is dissolved into your body during a dive and how much is released during surface intervals.

Most entry-level dive computers use the Reduced Gradient Bubble Model (RGBM). Suunto, the leader in entry-level dive computers uses this algorithm, along with Mares and Cressi. RGBM is relatively conservative and is designed for multiple dives over multiple days.

Dive Computer Modes

Dive computer modes are fairly standard across the board. Each manufacturer will list the modes their computers operate in. Be sure to fully read the computer’s instruction manual before use.

Here is a list of modes you’ll may see and what each one means:

AIR – Used for standard scuba dives with regular air.

EANx or NITROX – Used for diving with oxygen-enriched gas mixtures.

GAUGE – This mode acts as a bottom timer ONLY. It will show your time and depth, but does not include no-decompression limits or bottom time calculations. 

FREE (Freediving) – Designed for breath-hold diving (no tank). A unique sport in itself. Purchase a dive computer with a freediving mode if this interests you.

LOG – This mode acts as a digital log book. Dive computers can save details of past dives, such as maximum depth, average depth, total bottom time and temperature. Many computers allow you to download this information to your PC, tablet or even smartphone via cables or wirelessly.

PLAN – Used before a dive. Plan mode will indicate a variety of depths and no decompression limits based on your immediate dive history. This is also a reason why you should always use the same dive computer.

OFF – This mode can be used if you wear your computer like a watch. It will give you the time, but you can splash around in the water without tracking depth or time.

Air Integration

Computers with air integration let you pair your computer with a transmitter on your first stage or are built into the console if not using a wrist computer. You will then be able to see how much air you have in your tank on your computer during the dive.

It’s important to also have a traditional air pressure gauge in case the transmitter fails. Computers that allow air integration tend to cost a bit more than basic entry-level models and the price of the transmitter should also be taken into consideration before buying.

Nitrox Compatibility

You may not be nitrox certified yet, but it’s an option to be considered in the future. As you read this, you are breathing air, which is approximately 21 percent oxygen and 79 percent. Nitrox or EANx – Enriched Air Nitrox, is a gas mixture for diving that contains more oxygen and less nitrogen compared to your standard dive tank. That is to say, you could dive on a tank with 32 percent oxygen versus the regular 21 percent.

The primary benefit of scuba diving on nitrox is that your body absorbs less nitrogen at depth. This means you are able to extend your bottom times and no-decompression limits.

Almost all dive computers nowadays are nitrox compatible. Before buying, be sure to double check.

You may come across some computers that allow 100 percent oxygen, but those are used in technical diving. You will just need one that is compatible up to 40 percent oxygen.



Like all electronic devices, the battery will not last forever and it will eventually need to be replaced. In some dive computers, you can change the battery yourself,  but others require you to send it back to the manufacturer or to bring it to a licensed service centre.

You can choose a model that allows you to change the battery yourself if you prefer, but a note of caution, if you make an error, the warranty will be voided.


To avoid taking your computer to a dive centre and the risk of changing the battery yourself, rechargeable batteries are an option, though, not many entry-level computers have this option.

Watch Style or Console?

Dive computers can come in a watch style or be part of your dive console with the air pressure gauge.

The classic style watch computers tend to be large and chunky, but there are smaller and sleeker models available. You can wear these ones out to the grocery store or to the office. Only other divers will recognize it, so you might make an unexpected friend in your community! These are more comfortable options if you intend to wear it for extended periods. For example, when going on a scuba diving holiday, you can leave your daily watch safe at home and wear your dive computer instead.

When buying a dive computer, we prefer to recommend well-known dive equipment brands. See some of our most trusted brands for entry-level dive computers below.





We hope this helps you on your new adventures!

And lastly, as always, dive safe!

“Diving is an investment of time and money but the rewards can be life changing, literally.”

– Andi Cummins


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