Why You Need A Dive Computer

By David Fialkoff •  Updated: 12/29/20 •  8 min read

For many years, scuba divers have been using dive tables to control dissolved nitrogen levels and other vital parameters. Now, the old fashioned dive tables have been replaced by the use of a dive computer. These small pieces of equipment have made the sport of diving safer and accessible to everyone.

The dive computer allows scuba divers to calculate the time and depth of a dive and can help you prevent a dangerous condition called decompression sickness (DCS). Although DCS is usually mild and harmless, in some cases, it leads to paralysis, numbness, or even circulatory shock.

So do you need this device? Why should you use it? Read on, and you will find the answers.

What Does a Dive Computer Tell You?

This scuba accessory usually provides you with the following information:

Record Diving Depth

These small devices can tell you how deep you are diving, so you can make sure you do not exceed the maximum depth and do not put yourself in danger. Moreover, they can help you prove that you have stayed within the limits in case of damage to equipment.

Monitor Multiple Gases

If you are going to explore underwater caves or other dangerous scuba diving locations, you may need more than one scuba tank. This diving gadget can monitor the levels of oxygen in each separate tank, displaying the information on the screen.

Share the Information

With a dive computer, scuba divers can upload the gathered information on a dive onto their laptops and PCs. Moreover, you can also upload maps, photos, and videos of your dive activities and share them with your friends and other divers.

Provide Decompression Times

As was mentioned above, this device can also help you avoid decompression sickness by telling you how long you may stay at a specific depth. It will also tell you how to ascend and how long to stay at a particular depth to normalize pressure.

Air Transmitter

The air transmitter is an extra feature of some advanced models. It allows you to control the air pressure and can tell you how long you may stay underwater safely.

What Is the Best Dive Computer For a Beginner?

According to numerous reviews across different websites, Mares Puck Pro Plus is the best choice for beginners. But why is it so good? Let’s find out.


This device is an upgraded version of the Puck Pro dive watch. The manufacturer has improved its connectivity and navigation, and now you can connect it to your smartphone or laptop wirelessly via Bluetooth. Moreover, Mares has simplified the data exchange process and updated the firmware.

Technical Specifications

The Mares Puck Pro Plus records the last 36 hours of diving. The maximum depth is limited to 150m (about 500ft). Also, it allows you to switch between imperial and metric units.

Main Features


Mares Puck Pro Plus has all of the features a dive computer should have. With this device and its Bluetooth connectivity, you can easily access your data after each dive. It allows you to see information on the laptop without having to buy software and a USB cable.

Also, Puck Pro Plus looks more sophisticated and offers more colors to choose from. In general, this model is a great choice for beginning divers.



Is a Dive Computer Necessary?

Although this piece of diving equipment may be expensive to buy or rent, it is an essential item that every scuba diver should have. It has numerous functions and features that guarantee the safest diving possible.

Current Depth

Your current depth is probably the most vital piece of information on your display. If the water is crystal clear, you can be a lot deeper than you think. You must know your depth to dive safely within your limits and not go deeper than you planned to.

Rental items are often not working or not calibrated, and gauges on your gear are not as accurate as computers. Moreover, most computers can also tell you the water temperature, the maximum depth you reached, the current time, and the total dive time. Still, be aware that they do not know the boat’s rules or your certification depth limits.

No Decompression Limit

No Decompression Limit is another parameter you need to know. NDL is the maximum time you can stay at your current depth with no need for decompression stops. Usually, the NDL disappears when you are shallower than 10m (30ft).

You need to ‘shallow up’ when the NDL number gets lower. Even a few meters shallower will increase your NDL time significantly. Make sure to keep it higher than 2 minutes; otherwise, your computer will give you an audible warning to make a decompression stop.

Safety Stop Information

The dive computer can also help you plan your safety stops. It will tell you how long you should wait before ascending and will beep an alarm at you if you ascend too quickly during the safety stop, warning you to slow down.

Can You Dive Without It?

In some cases, you can dive without a dive computer:

Although waterproof dive tables are not as accurate as computers, they are a popular method for calculating safety stops and other parameters.

You do not need to worry about consuming too much compressed nitrogen or running out of air if you are shallow diving.

Still, you need to remember that it is not recommended to dive without a computer. Furthermore, it is even more important if you are using Nitrox tanks. They contain more compressed nitrogen, and the risk of decompression sickness is much higher.

Why Are Dive Computers So Expensive?

If you are new to scuba diving, the prices will surprise you. A good computer can cost from $200 up to a few thousand dollars, depending on its features. But why are they so expensive?

The main reason for such a high price is a lack of mass demand for these products. The scuba market is very limited; therefore, the manufacturers have to spread the development costs over a small number of units and set the selling prices pretty high to recover those costs. Less demand means less production, which eventually leads to higher costs.

Why a Dive Computer Is a Necessary Piece of Equipment

Reason #1: Safety

The computer tracks your depth, diving time, and other essential parameters, decreasing the risk of human error. With this device, you do not have to guess your ascent rate or calculate your no-decompression time. Moreover, it can determine how much time you have left before you run out of air, making the sport of diving much safer.

Reason #2: Ascent Rate Indicator

A built-in ascent rate indicator eliminates the ascent guessing game, which is typical for outdated dive tables. It uses visual and audible alarms to monitor your ascent speed, preventing the risk of decompression sickness.

Reason #3: Accuracy

Dive computers are much more modern and much more accurate than dive tables. They can track you minute-by-minute, automatically calculating no-decompression time. It helps you to stay safe underwater, as it takes into account not only the deepest part of your dive but also the shallower parts.

Reason #4: Dive Nitrox

If you are going to use Nitrox (Enriched Air), you cannot do without a computer with a built-in Nitrox mode. Nitrox dive tables are confusing, and even the most advanced divers can hardly understand them.

Reason #5: On-going Dive Log

A computer will keep track of your diving stats, making it easier to analyze your performance. Moreover, you can download them onto your laptop or PC and share them with other divers.

Reason #6: Longer Bottom Time

It is almost unreal to calculate the exact bottom time using only a dive table. As was mentioned above, they do not take into account the time spent at shallow depths. However, it is not a problem for the computer, as it can accurately calculate the time you can spend underwater.


A dive computer gives scuba divers the freedom to enjoy the diving experience more fully. It allows you to spend more time underwater without the risk of decompression sickness. For this reason, if you are serious about the scuba diving sport, I strongly recommend you purchase this piece of diving equipment.

David Fialkoff

David Fialkoff is the founder of Spearfishing.Live, a site that's dedicated to the sport of spearfishing. He is a full-time digital marketer and loves to spend time chasing fish underwater on the weekends.