What Is a Dive Computer & Do You Need One?

Rok Valencic

When I was getting ready for my Open Water Diver license, I came across the best dive computers in the PADI literature. Then, I heard people mentioning them when we were nearing the practical part of the course. My first thought, “What is a dive computer?” was immediately followed by, “Jesus, I’ll be taking a computer down there?”

I was panicking for no reason, though. A dive computer is an electronic wristwatch-sized device worn by scuba divers to help them track dive stats. I also didn’t need one either, at least not when I was starting out.

If you’re a complete beginner, you probably don’t need the best beginner dive computer either, and it’s perfectly fine to dive without one, but a computer can still be a very useful tool to put your mind at ease during dives.

What Is a Dive Computer?

A dive computer on a scuba diver underwater

A dive computer is a small device that scuba divers wear on their wrists or attach to their gear. It’s like a smartwatch for diving! A computer does a few important things to help keep you safe underwater.

First, it keeps track of how deep you dive and how long you stay underwater. This is super important because the deeper you go and the longer you stay, the more your body absorbs nitrogen from the air you breathe.

Too much nitrogen can be bad when you come back up to the surface because it can cause decompression sickness (also called “the bends”). The computer helps prevent this by calculating how long you can stay at a certain depth before you need to come up.

Instead of using old-school decompression tables (which are kind of like charts divers use to plan their dives), the dive computer does all the math for you. Plus, it also acts as a depth gauge, showing you exactly how deep you are at any moment during your dive.

What Is the Purpose of a Dive Computer?

This helps to prevent problems like coming up too fast, missing decompression stops, making the stops too short, or taking them at the wrong depth.

Every single dive computer does this because this is their main function. But apart from this, the best dive computers offer countless other features, where some are intended for more experienced divers who dive using multiple gases, and others for more convenient and comfortable diving.

This is a list of all the features you can find in dive computers, with my assessment of how important it is to have each one and why:

1. Alerts

Important
Alerts on your dive computer can warn you about important things like reaching your maximum depth, low air, or too fast ascents. These are crucial, especially when you’re starting out, because they help you stay safe underwater. Top-rated dive computers have vibration alerts, so you can feel them underwater where sound isn’t reliable.

Dive computer alerts

Of course, it’s totally doable to dive without alerts, which just means you have to keep an eye out for all these things, frequently check your pressure gauge, and monitor your depth and time underwater. But if you’re not used to doing all this, something can easily slip your mind, turning your whole dive plan upside down.

For example, I never had to pay much attention to any of this (except my own pressure console) when I was diving with a guide, which is how most people start scuba diving. But as I was getting ready for the first dive that would be completely under my control, I couldn’t have trusted myself to track all this effectively.

2. Computer/Phone Connection

Important
When you’re starting diving, this can be really helpful for tracking your progress, seeing how long and how deep you’ve dived, and learning from each experience.

Dive computer logs

This feature lets you download and review your dive logs on your phone or computer. It’s like keeping a diary of your dives.

Otherwise, the dives will all just blend together, especially if you only dive a few times a year.

As you get more experienced, the dive logs can become even more important because planning dives will include more details, and you will want to keep track of them.

3. Air Integration

Important for the highest comfort but not vital
An air-integrated dive computer can transform your dive into a much more carefree experience because it will monitor your tank pressure and let you know when to turn back on your journey. However, you can achieve the same thing by monitoring your pressure console yourself.
All the best high-end dive computers have air integration, but this also means they are pricier.

An air-integrated dive computer with transmitter

Air-integrated dive computers show you how much air is left in your tank. This basically replaces the need to check your pressure gauge console because the information is more conveniently available on your wrist.

It’s fair to point out that as soon as a dive computer has air integration, the price will skyrocket (~$1,000, plus you have to buy the air transmitter as well, adding another couple hundred dollars).

4. Digital Compass

Only important for navigating rugged terrain or finding dive locations (wrecks)
This isn’t a priority when you’re starting out, but it is worth considering if you plan on cave or wreck diving in the future so you won’t have to upgrade your computer. Most top-tier dive computers include a compass.

Compass on a dive computer

A compass on your computer helps you navigate underwater. This can be important if you’re diving without a guide (meaning you’re the guide), the reef you’re exploring isn’t just a straight line, and the accuracy of hitting the exit point matters.

However, if your spatial perception is moderately good, you can dive perfectly fine without a compass. For example, most of the dive computers I owned so far haven’t had one, and I never missed it much.

4. Nitrox and Multi-Gas Modes

Important only if you ever plan to tech dive
These modes allow you to dive with different gas mixtures, which can extend your dive time and reduce nitrogen absorption. This is advanced scuba diving and also requires additional technical courses. ALL best dive computers include multiple dive modes.

A dive computer with nitrox

As a beginner, you might not start with these right away, but they’re good to have as you progress and try new things. On the other hand, if you’re ok with diving a few times a year, you can skip this.

5. Smartwatch

Only important if you also want to use it as a smartwatch
Some divers want a two-in-one tool, a watch they use every day, and a dive computer. A smartwatch computer is normally more stylish but can sacrifice some comfort when diving. The Garmin Descent Mk2i and Descent G1 are two such examples.

Smartwatch dive computer

Depending on the smartwatch and its features, a smartwatch dive computer can do countless things besides keeping track of your dive.

You can have mobile notifications, contactless payments, music, GPS, apps for different sports, etc.

But, obviously, this also means a higher price. You are getting more features, after all.

7. Thermometer

Not important
This just keeps track of water temperature when you dive, which can be interesting to look at in dive logs but doesn’t help much during the dive itself.

A dive computer thermometer

This is only relevant if you dive frequently, in different conditions, and need to keep track of the right gear choice for the next time you return to a dive spot (drysuit, gloves, …).

I like to look at the temperature in my logged dive data, but more out of curiosity than anything else.

8. Configurable Decompression Algorithm

Not important until you are an experienced diver (maybe not even then)
This is fine-tuning your computer to your gas consumption and personal preference. It can mean a difference in how soon the computer tells you to start heading back to the surface, but you won’t notice a difference as a beginner. Most top-of-the-line dive computers include a configurable Bühlmann algorithm.

Configurable algorithm on a dive computer

You want to stick to standard settings at first, but as you gain experience, having the option to adjust for your own comfort and safety can be valuable.

Can You Dive Without A Dive Computer?

Yes, scuba diving without a dive computer is ok but it is very limited.

As you begin diving, you will probably keep to shorter dive times and shallow dives until you get a few dives under your belt and get the hang of things.

Although I wouldn’t advise diving without dive computers (I’ll explain why in a moment), it can be done relatively safely in the following scenarios:

  • For short and shallow dives (60 feet or less for less than 60 minutes), you usually don’t need to worry about decompression. In these cases, you mainly need to pay attention to your pressure gauge to know how much air you have left in your tank so you’ll know when it’s time to head back up.
  • If you’re diving with an instructor who knows you well, understands your experience level, and will lead the dive, you might not need a dive computer either. However, this will limit you to short and shallow dives again. The instructor will handle all the monitoring and ensure the dive stays within safe limits.

Either way, if you dive without a computer you need at least a pressure gauge (which is standard equipment anyway), and a depth gauge, so you don’t accidentally exceed you maximum depth limit.

So, while beginner diving without a computer is manageable, it’s certainly much more convenient to dive with a computer. It will also put your mind at ease, knowing that everything is under control. Just make sure you buy a high-quality beginner dive computer, not something that will fall apart after 20 dives.

Do You Need a Dive Computer?

If you’re in the process of getting your first diver’s license, you don’t need a computer yet. You will be diving with your instructor, and it’s better that you pay attention to them and the dive instead of worrying about the computer.

After you complete the course and start diving more independently, my advice is to rent dive computers from a local dive center. They will show you how to operate it, and you will get the chance to see how different scuba diving computers work.

When to buy a dive computer
When you become comfortable diving and have used a rented computer a few times. The need for a dive computer will increase with your desire for more independent diving.

Of course, you can also buy a computer as soon as you begin diving. That way, you will already be used to one by the time you become more independent. But it’s harder to know which dive computer is the best for you without some experience.

As soon as you plan to dive longer or deeper (which you will soon enough, even if you’re just starting out, trust me), decompression becomes more important.

Without a dive computer, you’d need to use dive tables. These tables help you plan your dive and avoid staying too long at depth to prevent decompression sickness.

But tables are cumbersome, and at this point, having your own computer that you know can set to your requirements and can always have on you becomes much more convenient. You will also be able to dive with your mind at ease.

What Is the Difference Between a Dive Watch and a Dive Computer?

Tissot Seastar Powermatic 80 dive watch

A dive watch is primarily a watch that is water-resistant to great depths. That means it looks like a watch, works like a watch, and is used to track dive time. This is NOT a dive computer, however.

Garmin Mk2i smartwatch dive computer

There are some smartwatch dive computers, which look like regular smartwatches but also have the full functionality of a dive computer. The Garmin Descent Mk2 and the Apple Watch Ultra are two such examples.

Shearwater Teric dive computer watch

There are also dive computers that look like watches. This means that while they weren’t designed primarily as watches, they can be used as such anyway. A watch-style dive computer looks more stylish than regular dive computers but has the full functionality of a dive computer. For example, the Shearwater Teric and the Suunto D5.

Shearwater Perdix dive computer

Finally, there are dive computers that are just that. These are designed to work as dive computers only, which means they are bulkier, more sturdy, and usually come with larger displays than you would want on something that looks like a watch. For example, the Shearwater Perdix and Peregrine.

Other Types of Dive Computers

There are three types of dive computers (not counting analog gauges for obvious reasons):

Wrist Dive Computers

This is like the Shearwater Perdix example above. These are the most convenient for diving because they are on your wrist, and you don’t need to blindly search for them, as you can with the pressure gauge console. They also come with large screens for easy reading.

Watch Style Dive Computers

This is like the Garmin or the Shearwater Teric above. They can be more watches than computers or more diving computers than watches, depending on what you prefer. Their main characteristic is that they look like a watch while still offer dive computer functionality. The downside is that screens are usually smaller, which can mean cluttered dive data.

Console Dive Computers

A console-mounted dive computer

As the name suggests, a console dive computer is mounted on your console next to the pressure gauge, compass, or whatever else you might have on your console. Some tech divers prefer these because they are more bulky, more sturdy, and have a direct connection to their tanks.

How to Choose a Dive Computer?

Choosing the right dive computer is important because even the cheapest ones aren’t cheap, and you don’t want to be buying a new one after six months because you didn’t think things through the first time.

On the other hand, how can you know what you need without extensive experience with different diving computers?

My advice is this:

1. Decide whether you want to buy a computer for beginners (easier to use, fewer dive features), or do you see yourself moving towards more advanced, technical diving in the near future (more dive features, support gas mixes for deeper and longer dives)?

Don’t go deep into specific features; it will just confuse you unless you already know exactly what you want.

2. Do you want to use it just as a dive computer or as a (smart) watch as well? Buying one that looks and works like a watch is usually more expensive, but then again, you’re buying an everyday tool, like a new phone.

3. What’s your budget? Good entry-level diving computers start at around $300 but have the fewest features and the least style. Mid-range computers, which are more than enough for beginners and entry-level tech divers, start at around $500, while high-end computers are $1,000 and above.

When you have all three answers, head to my buyer’s guide for the best dive computers. There, you will find computers in categories based on these three things, which will help guide you toward finding the best computers for you.

Or, you can see the list of the best dive computers for beginners if you already know you’re not interested in tech diving in the near future.

Conclusion

There you go! I hope I was able to help you understand what is a dive computer in an easily understandable way and, more importantly, whether you need one at this point.

If I missed anything or you have additional questions, don’t be afraid to drop me a message. I’ll be happy to point you in the right direction!

Rok Valencic

Rok Vale

I’m a sports enthusiast who enjoys spending as much time underwater as possible. Be that diving, snorkeling, swimming, or just falling off the surfboard. I’m a licensed PADI diver and a licensed fitness instructor. I also have a degree in physics to unnecessarily complicate my life.

FAQ

No. Getting entry-level PADI certification doesn’t require a dive computer because you will be doing everything with an instructor who will monitor your dives. Advanced-level PADI courses also don’t require a dive computer, although it’s recommended that you have one because it’s assumed you will be using one when you’re diving independently. But you can always lend a computer at the dive center where you’re taking the practical part of the course.

A high-quality diving computer can last well over 10 years. This primarily depends on the build quality and the components used in the computer. Generally, a computer from a trusted dive computer brand like Shearwater will stand the test of time. If you buy a cheaper computer, then you’re gambling with the life expectancy. It can still be 10 years, or it can be 50 dives.

Diving computers are expensive because they are built to withstand very harsh environments (high pressure, water, corrosion, …). They also include a lot of gadgets that aren’t cheap on their own (pressure gauge, depth gauge). Lastly, the scuba market isn’t very big, which means less demand, less production, and, in turn, higher prices.