What’s the Difference Between Scuba & Deep Sea Diving?

Last Updated: February 8, 2023

The main difference between scuba and deep sea diving is the individual’s ability to explore as deep diving will allow the diver the reach much greater depths thanks to advanced equipment. Scuba diving is much more restrictive in terms of exploration depth.

Here I will take you through all of the differences between deep sea diving and scuba diving to help you understand more about them.

Scuba Diving vs Deep Sea Diving

The biggest difference is the maximum depth that can be achieved on the dive. Typically the most shallow form of diving is snorkelling, which then becomes scuba diving which allows you to dive deeper before becoming deep-sea diving.

There are also differences in the equipment needed to go scuba and deep sea diving. So, first let me explain what scuba and deep sea diving is in more detail.

What is Scuba Diving?

The word “scuba” is actually an acronym and refers to the equipment needed to complete the activity. It stands for Self-Contained Underwater Breathing Apparatus and refers to the equipment that divers use to be able to breathe freely underwater thanks to the tank of air that they carry on their backs and the respirator.

The system itself is also referred to as an “aqua lung” and was developed in the 1940s by Emile Gagnan and Jacques-Yves Cousteau before being adapted in the 1950s by Ted Eldred. This adaptation has allowed the equipment to be used worldwide today.

It consists of a high-pressured air tank that contains the gas needed to breathe. This is then hooked up to a two-stage respirator which is placed into the diver’s mouth, allowing them to breathe normally.

This type of equipment is referred to as “open-circuit” meaning that once the gas has been inhaled by the diver it is then released into the water in the form of bubbles.

You can also find “closed-circuit” breathing apparatus where the used air is recycled and few or no bubbles are released into the water.

In order to be able to dive by yourself, you will need to complete and pass a training course that will allow you to dive to a maximum depth of 60 feet (or 18 meters) with a diving partner.

Once you are certified to go scuba diving you will be restricted in terms of depth both by your training and your gear. When inhaling pressurized gas it is important that you do not push the equipment beyond its limits.

For example, scuba diving will not permit you to dive to a depth where you will need to depressurize or to explore any structure such as caves or wrecks that are not in the line of the view of the surface.

What is Considered Deep Sea Diving?

If you want to explore the sea beyond the limits of scuba diving (typically anything deeper than 40 meters) then this becomes deep-sea diving.

It is also referred to as “technical diving” and requires more training as well as highly-specialized equipment to ensure that you are safe on your dive. The pressures at these depths can be very dangerous if you are not properly trained to handle them.

Training to become a deep-sea diver will cover not only the difference in equipment between regular scuba gear and the more advanced tools for deep diving but also the dangers of diving to such depths.

You will be taught how to deal with emergencies at extreme depths to help you cope in the unfortunate case that such an emergency occurs for real. For example, you will be taught how to have contingency plans in the case that your deep dive does not go according to plan.

So, although both kinds of diving carry their own risks, deep diving is much more dangerous due to the pressures faced at these depths and the need to decompress correctly before resurfacing. You will need to be certified to perform deep dives which will take much longer than scuba certification.

What Do Deep Sea Divers Do?

deep sea wreck diving

Deep divers are those who carry out technical dives, also referred to as non-professional deep sea dives. These are much deeper than recreational dives and can go beyond the NDL limit of 40 meters below the surface.

This means that they are also allowed to explore overhead structures such as wrecks and caves which scuba divers cannot.

This type of diver will descend into the sea slowly, adjusting their body to the new pressure as they go. This ensures that the diver is safe at all times. Safety is the most important part of any dive, but it is absolutely crucial to a deeper sea dive.

This means that divers take a lot of time and care over curating their dive plans to ensure that they are aware of the depths they will reach, their route, their maximum depth, the state of their equipment and have backup plans in the case that something goes wrong.

For example, they must take into account the time needed to decompress before returning to the surface to reduce the risk of getting decompression sickness. This is not something that needs to be taken into account with recreational diving.

Many people enjoy deep diving because it gives you the opportunity to explore places underwater that most people have not gone before and to experience a silence like no other. You are truly immersed in the world under the water and can relax and take a break from daily life.

How Deep Can Deep Sea Divers Go?

The general range for what is considered to be a deep sea dive is anything between 18 and 40 meters below the surface of the water. Typically 40 meters is considered to be the maximum depth that anyone can safely reach given their training and equipment.

It is important that you recognize the limits of your dive before you begin so that you do not put yourself in any dangerous situations and to keep your partner safe as well.

If the conditions are not perfect then this will obviously affect the maximum depth that divers are able to reach and will need to be taken into account when calculating the dive.

Deep Sea Diving Gas Mixtures

deep diving gas mixtures

Another difference between scuba and deep sea diving is the equipment needed. With scuba, it is perfectly fine to have a tank full of regular air as this will not be subject to significant pressure at shallow depths.

However, when it comes to deep dives you will need to take into account the depth of the dive to figure out the correct gas mixture.

Technically, regular air can be used up to a maximum depth of 50 meters underwater, although this is not always the best choice as nitrox is often used. Anything beyond 50m then requires the use of trimix (a combination of oxygen, nitrogen and helium).

At deeper levels you run the risk of nitrogen narcosis which is when the nitrogen in your gas tank becomes so pressurized that it can begin to act like an anaesthetic and cause you to become unconscious. Obviously, this poses a great health risk and so higher level of oxygen and helium are included to combat this.

The addition of helium into the gas tank effectively reduces the nitrogen percentage and because helium does not act as an anaesthetic when under pressure it reduces the nitrogen’s effects and makes the gas safe to breathe.

Depending on the exact depth of the dive you will need to calculate the exact percentage of different gases needed in your tank. You will learn how to do this in your deep diving training course.


Scuba diving is an activity that many of us are familiar with, you may even have tried it on holiday. Here you are able to reach a deeper level than you can with snorkelling as the open-circuit aqua lung allows you to breathe normally under the water.

However, scuba diving has a maximum depth and anything beyond this will take you into the realm of deep sea diving. That is considered as anything that goes below 18 meters from the water’s surface. You will need to complete a training course to ensure that you are aware of the risks involved and learn how to handle the new equipment.

At the depths of a deep sea the gas mix in your tank has to be right to ensure that you are not knocked unconscious by the nitrogen, or that you suffer from oxygen toxicity (when you are exposed to too much oxygen). Typically, deep sea divers will rely on trimix which adds helium into the mix to help combat the anaesthetic effects of nitrogen.

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