What Is A Dive Computer?

Scuba diving is one of the best and most rewarding sports you could ever take part in.

Who can forget their first dive? That pure sensation of empowerment that comes with weightless exploration is a life-changing experience!

If you’re a new diver, there’s a good chance you’ve heard about dive computers but don’t know what they are or what they do.

Dive computers are an awesome piece of equipment for any scuba diver and make diving much safer and more fun.

In this post, we’ll explain what is a dive computer and why you need one. By the end of this post, you’ll know everything you need to know about dive computers and be ready to buy one!

⌚️ 1. What Do Dive Computers Provide

So this mysterious piece of equipment that you see on most divers, what exactly does it provide and why in the heck does everyone keep looking at it during their dive? It is like the underwater version of a phone!

Well, it holds vital information that will make your life easier. Much easier than constantly pulling your depth gauge out of your pocket or holder. You just hold your wrist in front of you, and voila! All the information you need is right in front of you.

Personal dive computers provide vital information like:

  • Depth
  • Time spent underwater (bottom time)
  • No-decompression limits
  • Water temperature
  • Ascent speed
  • Time in and out
  • Some models are air integrated dive computers that show how much air you have left
Scuba diver checking dive computer

❓ 2. Why Do I Need A Dive Computer?

Safety, safety, safety!

Safety is the number one priority when scuba diving. And when you are 30 meters underwater at 4 atmosphere of pressure, even a tiny mistake can have disastrous consequences.

Dive computers give you the security that you can truly rely on, reducing the potential for human error. Your dive computer will be your best buddy, in fact, so good you’d be lost diving without it.


Even experienced divers make mistakes. Dive computers take away the possibility of any errors in calculations. They have sophisticated depth gauges that track how long you’ve been underwater, at what time, and how much no-decompression time you have left.

The dive computer’s algorithm also monitors your maximum depth and gives loud, clear alerts when you exceed your allowed time at a certain depth.

Extending No-Decompression Limits – No More Dive Tables!

Remember the dive tables from your Open Water Course? They give you the maximum time allowed at a certain depth. However, when you dive, it is literally impossible to stick to a set depth, losing you valuable bottom time.

Some divers might even remember the wheel. The wheel was used in the place of dive tables to calculate no-decompression limits for multi-level diving. It was a pain in the butt learning the wheel. But you don’t need to do that anymore.

Dive computers are just like the wheel but on steroids!

They have sophisticated algorithms that calculate how much time you have spent at each depth, then calculate how much time you have left, giving you plenty more bottom time without jeopardizing safety limits and risking decompression sickness.

Ascent Speed Monitoring

Remember the absolutely vital rule, Slowly Ascent From Every Dive? A slow ascent is a non-negotiable part of scuba diving, period. It is the number one rule and not to be violated.

A dive computer will accurately monitor your ascent rate and beep loudly when you’ve gone too fast. Some dive computers are so sensitive that they beep even when you raise your arm!

Rather than following your dive guide or estimating your ascent rate, your dive computer gives you a 100% way to measure your ascent rate accurately.

Dive Logbook Entries

Finally, your dive computer will know it all. They contain all the dive data from every single dive since the beginning of time.

After each dive, simply ascend and check the dive data on the dive computer to accurately fill in your logbook.

Also, in the event of any unfortunate accidents, dive computers are the first thing that is checked for information on what went wrong.

Checking dive computer

🤿 3. What Does A Dive Computer Do?

So what exactly do dive computers do? Aside from the complicated algorithms, simply put in a nutshell, dive computers:

Calculates Maximum Allowed Bottom Time

  • What is your residual nitrogen level from your last few dives
  • How long you have for your next dive, and at what depth
  • Throughout the dive, how long you have at each depth
  • What is your max depth allowed on every dive considering your residual nitrogen levels from previous dives and surface interval
  • Displays total dive time, depth gauge, and decompression limit throughout the dive
  • How long before you go into decompression
  • If you go into decompression by mistake, what are the required decompression stops
  • Dive computers lock you out when you go into decompression, you will not be able to dive with it for 24-48 hours depending on how long you exceeded your NDLs.


  • Monitors ascent rate
  • Most dive computers allow 30ft/minute
  • Alerts (loudly and annoyingly!) if you ascend too fast
  • Displays depth gauge at all times, giving you an easy way of checking depth at the safety stop
  • Calculates time for the safety stop
  • Alarm goes off when safety stop is done
  • Many dive computers have a suggested deep stop in addition to the safety stop if deep diving below say, 70 ft / 25m
  • Other dive computers only offer the 5meter/3minute safety stops
  • Dive computer algorithm will not allow you to dive again if you violate any ascend limits

Pressure Gauge

  • Computers with air integration will display your air pressure at all times

Dive Log

Contains all the data recorded throughout the dive for your logbook like:

  • Time in and out
  • Depth profile through the dive
  • Bottom time
  • Temperature
  • Maximum depth
  • Complete dive profile

🤔 4. What to Consider When Choosing a Personal Dive Computer?

Did we get you thinking about getting one? *wink*

We hope so! Now let’s go on to what makes a good dive computer and finding the right dive computer for you.

Wrist vs Console Dive Computer

The first is that there are two types of dive computers- wrist and console. Console dive computers are larger and look like oversized watches. They are big, bulky, and are usually more affordable, although this isn’t a hard and fast rule.

Wrist dive computers are smaller and attach to your wrist. They look like dive watches. Don’t have them confused with a dive watch!

A watch style dive computer is typically more expensive than a console computer, and more popular with scuba divers.

Dive Computer Key Features

The next thing to consider is what type of diving you will be doing. Not all dive computers are created equal!

Dive computers come in three different flavors- Recreational, Technical, and Mixed Gas. Recreational dive computers are designed for single tank dives within the recreational diving limits of depth and time. These dive computers will suit all recreational divers regardless of experience level.

More advanced dive computers for the experienced diver can calculate decompression, multiple gas mixes, switch between breathing gases and give a decompression plan.

However, if you aren’t technical diving and are purely recreational diving, there’s no need for a fancy (and pricey!) technical diving computer.

For recreational diving, look for these features:

  • Full tracking of dive profile across repetitive dives
  • Air integration is a nifty little additional feature, but be prepared to pay more for air integration!
  • An air integrated dive computer will have a transmitter that attaches to your first stage and monitors the tank pressure, displaying how much air you have left, taking the role of the air pressure gauge and letting you know your air consumption.
  • Easy to read display. You don’t want to be squinting when you are 30 meters underwater!
  • Nitrox. Most computers these days have nitrox mode but it’s good to check
  • Battery life
  • Compass
  • Price, of course, you don’t want to break the bank! Console computers have a tendency to be more affordable and beginner-friendly.

👍 5. How To Use A Dive Computer

A dive computer takes a while to get the hang of, but once you do, it’s off to the races! It will be your best dive buddy and accompany you on every dive, guaranteed. It gives so much convenience and comfort that it would be difficult to consider a dive without one.

Each dive computer has a different operating interface, although there are some similarities with certain manufacturers. Your dive computer will come with a manual that looks intimidating at first, but once you go for a few dives, you’ll get the hang of it in no time.

  1. A dive computer will activate dive mode when it is under slight pressure, usually at about 1.2 meters (4ft). This is to prevent it from logging a dive when you say, are swimming or in the shower.
  2. Once activated, your dive profile is automatically logged, and your screen will start displaying your current depth, total bottom time, no decompression limit, how much dive time you have, and other useful information that you can quickly toggle depending on which button you hit.
  3. You cannot toggle out of the dive mode on your current dive, only switch between screens that display different dive information.
  4. Once on the surface, your dive computer will go into surface mode. You can now check your dive data, input it into your dive log, plan your next dives, and check your no-fly time.
  5. You can also sync the dive data with your laptop or phone to log your dives or analyze your profile and air consumption if you have air integration.
Setting the dive computer

🏢 6. Choosing A Dive Computer Manufacturer

When shopping for your new dive computer, keep in mind that manufacturers use different algorithms. Some use more conservative algorithms than others.

It is surprising how many different algorithms are in the market, considering it is the single most important feature that is taking care of your safety when diving and reducing the risk of decompression sickness.

More conservative models will calculate a slower ascend rate with more and longer safety stops.

You can also change the settings on your dive computer to select a more conservative algorithm depending on your health, physical condition, age, and diving experience level, whatever makes sense to you!

Some brands like Aqua Lung are known to have a more liberal algorithm, while brands like Sunnto are known to use a more conservative model.

💭 7. Final Thoughts

So, wanna get a dive computer now? We promise, it will be one of the best purchases you make as a diver, right after your mask.

Whether you are diving or free-diving, you want to see your depth, it is always nice to know! Why pull out your pressure gauge to check your depth instead of having it right in front of you? Wouldn’t you want to be admiring the underwater world instead?

Now you know what to look out for when shopping for your dive computer, get out there and look for one!

Thanks for reading, and good luck with your hunt for your dive computer. Happy bubbles!

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