SSI Decompression Diving Speciality: Expand Your Limits in a Single Tank!

Are you thinking about a tec diving course but aren’t quite sure if it’s for you? Or maybe you’re a certified dive guide looking for your next challenge? 

In any case, the SSI Decompression Diving speciality could be exactly what you’re looking for.

If you’re at least 16 years old, have 24 dives, plus your deep and nitrox specialities, you can go ahead and enrol in the SSI Decompression Diving course.

Let’s take a look at exactly what you can expect during the course.

What is the SSI Decompression Diving Speciality?

The SSI Decompression Diving speciality enables you to:

• Independently plan and conduct dives to 40 metres, in a recreational equipment configuration, with an equally or more qualified buddy
• Accumulate up to 15 minutes of decompression time (based on “backgas”—more on that later!)
• Use one decompression gas in a separate stage tank, filled with a maximum of 40% Nitrox

In other words, an SSI Deco Diver can dive deeper and stay longer.

No more will you need to worry about overshooting your No Decompression Limit (NDL)—now you can chill in the deep and enjoy the view!

It’s important to understand that the SSI Decompression Diving course is not a technical diving course. It’s a recreational speciality, just like deep, nitrox or navigation.

It’s designed to expand your limits while keeping you in the same configuration you know and love—a single tank. That means you don’t need to worry about the weight of a twinset before enrolling in the course. 

Alternatively, if you’re already a recreational sidemount diver, you can complete the course in sidemount configuration. That way, you can enjoy the balance, flexibility and freedom of sidemount while relaxing in the deep.

While your base configuration stays the same, there is one new piece of equipment you’ll be introduced to during the course: a decompression stage tank.

For this course, we like to use a 6 litre stage tank, which is about half the size of the standard 11 litre tank you’re used to diving with. Its size makes it easier to handle in the beginning—so much so that you might not even notice you have it with you!

As already mentioned, the SSI Decompression Diving course can fit many purposes. While we believe that any diver with the right attitude can become an excellent technical diver, we understand that not everyone wants to. However, even if you don’t want to make the full transition to tec, you should still be able to expand your limits. That’s where the SSI Decompression Diving course comes in.

If you fit one of the following categories, the SSI Decompression Diving course could be a great next step:

• You already have 24 dives, deep and nitrox specialities, and are looking to become an SSI Advanced Open Water Diver (AOWD)
• You’re already an AOWD, Stress and Rescue Diver, or a dive guide, looking for the next challenge
• You’re thinking about a tec course but aren’t sure if you’ll like it
• You want to stay deep for a longer time safely
• You simply want to expand your knowledge and become a better diver

If one of these cases sounds like you, consider the Deco Diver course for your next diving holiday.

What is Decompression Diving?

As you already learnt in your Open Water Diver Course, the nitrogen in the gas we breathe dissolves into our tissues while we’re underwater. This is because of the higher pressure underwater, which effectively pushes the nitrogen into our lower-pressure tissues.

When we begin to ascend, the reverse process happens. The nitrogen dissolved in our tissues begins to be released out of our tissues. This is because the internal pressure of nitrogen in our tissues is now higher than the ambient pressure. 

This process, known as “on-gassing” and “off-gassing,” happens every single time we go diving. Whether it’s a 5 metre dive or 40 metre dive, on-gassing and off-gassing occur.

The deeper and longer we stay underwater, the more nitrogen will dissolve into our tissues.

At a certain point, we will have too much nitrogen in our tissues for us to be able to make a direct ascent to the surface. If we were to ascend directly to the surface, the nitrogen could begin to come out of our tissues too quickly, which can cause gas bubbles to form—this can cause decompression sickness.

Instead, when we have too much nitrogen in our tissues, we simply need to make a slower ascent. This gives the nitrogen enough time to come out of our tissues at a safe rate. During this type of ascent, we stop for a certain amount of time at regular depth intervals, to help the nitrogen come out safely.

This process of nitrogen off-gassing is known as “decompression” and dives that require decompression stops during the ascent are known as “decompression dives.”

Voilà, the SSI Decompression Diving course! 

What Skill Level is Required for the SSI Decompression Diving Course?

As already mentioned, the SSI Decompression Diving course isn’t a technical diving course. It’s designed for recreational divers wanting to explore the deep safely.

However, it’s important to understand what decompression diving is and what skill level is required to conduct these types of dives safely.

Decompression dives are a type of “overhead” dive. Just like a wreck or a cave dive, decompression dives prevent you from making a direct ascent to the surface at any time you want. Instead, you need to ensure you’ve completed the time at each decompression stop before surfacing.

For this reason, it’s important that you feel comfortable in the water. That means:

• You have good control of your buoyancy and are able to hold your depth without having to focus on it
• You’ve mastered the skills you’ve been taught so far—ascents, descents, mask and regulator skills should be pretty easy for you
• You have depth and situational awareness while diving

We definitely don’t expect you to be perfect from day one—much of the course will be spent fine-tuning your buoyancy and position in the water, pushing you to the next level.

But you should start the course feeling like you’ve already mastered the skills you’ve learnt so far and that buoyancy comes easy to you.

That way, it’ll be double the fun.

Course Schedule

So, how does the course work?

How long does a SSI Decompression Diver course take?

Firstly, the course takes a minimum of 3 days to complete.

By SSI standards, the course consists of a minimum of 1 confined water dive and 3 open water dives. However, we like to do 4 open water dives, to give you more time to fine-tune your skills under instructor supervision and to ensure you’re more comfortable at the end.

Keep in mind that we fit courses to our students, not students to our courses. We believe that every student is different and requires a separate approach to match their learning style. And with the flexibility of the SSI system, it’s easy to do this.

That means that while the minimum standards enable us to complete the course in 3 days, it might take longer. Depending on your skill level, course schedules can change. We don’t run a so-called “course factory” and are happy to add an extra day to your training schedule to help you reach the necessary skill level.

Day 1

On the first day of the course, we begin with an equipment configuration workshop.

During this session, you’ll be introduced to different equipment configuration philosophies, including the pros and cons of certain equipment configurations. We’ll also include a stage workshop during this session, teaching you how to build and configure your stage tank. 

This session will also start to introduce you to the wider concept of decompression diving and the mindset needed to conduct these types of dives, as well as some theory.

After the equipment configuration workshop, we’ll jump in the water for a slightly longer confined dive than you may be used to.

During this dive, we’ll stay in the shallows, practising advanced buoyancy control, key emergency skills and stage handling. This includes skills such as:

• DSMB deployment
• Out-of-gas scenarios
• Stage removal and replacement
• Switching to your decompression gas
• Controlled ascents and descents

After the dive and a well-deserved break, we’ll jump into some theory in the classroom.

With the SSI system, you’ll be able to study all of the theory before you even step foot in the dive centre, using the SSI app. That means less time studying and more time diving while you’re with us. However, we like to go through some of the key concepts again, adding the knowledge of our experienced instructors, to put what you’ve read into practice.

Some topics we’ll cover include:

• Dive planning
• Oxygen toxicity
• Inert gas narcosis 
• Decompression sickness
• Decompression models 
• Inert gas laws

We like to break the theory up over the three days, giving you time to understand the concepts.

Day 2

If everything went well on day one, two dives are on the menu for day two.

On day 2, we’ll begin to focus on planning decompression dives and how to dive a staged decompression profile.

But we won’t jump into real deco dives just yet.

Instead, we’ll conduct two simulated decompression dives. That means we’ll create a dive plan with staged decompression stops during the ascent, but we won’t actually stay long enough in the deep part to incur any “real” decompression.

These simulated deco dives enable you to practise a staged decompression ascent without actually having any real deco to do, creating a safe training environment. These dives also give us time to repeat all of the new skills you learned on day one, allowing you to master them.

This day is mainly taken up with dive planning, diving, more dive planning, more diving, and a bit of theory sprinkled here and there!

After a good meal in the evening, you’ll sleep well after day 2!

Day 3

If the simulated decompression dives went well on day 2, then there’s only one thing left for us to do on day 3: actual decompression dives!

This is where the fun really begins, as we can begin to stay much longer than ever before at our maximum depth of 40 metres.

The day will consist of two dives to 40 metres. The first dive will be led by the instructor, enabling you to see how a real deco dive is conducted. For the second dive, you’ll be put in the driver’s seat, leading the dive and giving you the confidence necessary after the course to conduct deco dives with an equally or more qualified buddy.

During the dives, you’ll be given some emergency scenarios, putting into practice what you’ve learnt. 

For the real decompression dives, you’ll be able to accumulate a maximum of 15 minutes of decompression time. Decompression time is simply the total number of minutes spent on all decompression stops.

It’s important to understand that for the SSI Deco Diver course these stops are calculated on your backgas, rather than your deco gas.

Your backgas is simply the gas mixture in the single tank on your back. For us, this is either air or Nitrox 28% for 40 metres. However, in our stage tank, we will have Nitrox 40%.

Some people think of the stage tank as a “bailout” tank. In other words, it’s extra gas that you only use in an emergency. However, the gas we carry in stages during decompression dives is a “deco gas,” not a bailout gas.

Quite simply, that means that we will always switch to our deco gas during our ascent. This deco gas has a higher percentage of oxygen inside—for us, Nitrox 40%—which helps to eliminate the nitrogen in our tissues faster than if we were to continue breathing our backgas. This means our decompression time will be finished quicker compared to if we were to continue breathing our backgas.

But to make our dives during the course more conservative, we leave our dive computer in backgas mode for the entire dive, while breathing our deco gas. This means that our dive computer gives us more decompression time than necessary (as it thinks we’re breathing backgas, rather than our deco gas), making the dive even safer.

At the end of day 3, it’s time to pat yourself on the back for all your hardwork and celebrate with your preferred beverage of choice! 😉

Extend Your Limits with Lagona Divers: Deco Diving without a Tec Course

Whether you’re looking for the next challenge or simply want to spend more time watching the turtle at 40 metres, the SSI Decompression Diving course. is a great way to get there.

If you’re planning your next diving holiday, you can prebook the course or include it as a package…. and already start the e-learning at home.