Great! You have decided to get certified in scuba diving and are weighing up the options of a scuba diver vs open water certification. What are the benefits of getting certified? Let’s take a look at the differences between the two options.

Scuba Diver vs Open Water Certification

The quickest way to describe the broad differences between these two certifications is that Scuba Diver is Level 1 and Open Water is Level 2. The latter allows for a little more freedom and depth. During open water, you do more confined skills training and generally four vs two open water dives. This means you will gain more experience during training.

Here’s a quick comparison table to highlight the main differences:

For a lot of people the open water certification depth is what entices them to go for this certification. Furthermore, as an open water diver you can dive with your friend that is also certified. They need to be at a minimum the same level or a higher level, such as advanced open water diver certified.

Read More: Open Water Diving Certification Facts

Which Certification Should You Choose?

So, why do people go for one or the other? I can’t tell you which one is better for you. For some people, it is simply a choice of not committing to 4 open water dives. The most common question I get during sign up is what if I don’t like it?

A fair enough concern. As an instructor, I know that most people either spit out their regulator in the pool and knew immediately that it is not for them or they end up absolutely loving it!

If you feel that you want to start as a scuba diver for your own comfort, do that. Most dive shops will be able to upgrade you on the fly by simply continuing for another day or two.

Another common concern is depth. Some people are not comfortable to go deep and prefer the 12-meter maximum depth limit. After all, you should always respect your personal limits.

This is what scuba divers do to ensure their own safety.

Sometimes it is simply a question of time and budget. A scuba diver course can generally be completed over two days and is a little cheaper compared to the open water course, albeit not by much.

In a tropical dive destination, you can get your full open water certification over three days.

Which Training Agency Should I Choose?

Most people have heard of a PADI Open Water certification. This is because it is the largest global recreational dive training organization. It was founded in 1966 and has done an incredible amount of marketing. So much so, that people often ask to get their PADI as opposed to their diver certification.

I trained with SSI up to Rescue diver. I asked my Divemaster mentor at the time what the difference is and he said that they are for practical reasons the same, he said “we both teach blowing bubbles”.

Also, PADI and SSI have the same requirements for these two courses. You need to be a minimum of 10 years old and be able to pass a 10-minute survival float for the scuba diver level.

For open water the age limit is the same, however, you also need to complete a 200-meter swim.

If you choose RAID, which again is extremely similar at recreational levels, you need to be a minimum of 15 years old for scuba diver as well as pass both the 10-minute survival float as well as the 200-meter swim.

There are many different training agencies all offering very similar training courses. The WRSTC defines minimum global standards in recreational scuba diver training.

So, when deciding between a scuba diver vs open water certification, it comes down to your budget, time and goals. Remember you can always start out as a scuba diver and upgrade or continue to open water at a later stage.

How many years does a scuba tank last? Making sure your equipment is in working order is every certified diver’s responsibility. The cylinder holds your air, so it is natural to want to verify its integrity.

Read More: What Should Divers Do For Their Own Safety?

Let’s have a look at how divers do this. We will also learn the possible lifespans of scuba cylinders.

Want to know how long a scuba tank will last for a dive? Read More: How Long Does a Scuba Tank Last?

How Many Years Does a Scuba Tank Last?

I have witnessed aluminum tanks that have successfully passed hydrostatic tests 3-4 times. This means the tank is 10 to 15 years old. The manufacturer conducts the initial hydrostatic test. Subsequently, tanks need to pass these tests every 5 years. Certain parts of the world require more frequent hydrostatic testing.

In the US, the DOT (Department of Transportation) controls scuba cylinders.

While wrong, many dive shops agree that a properly cared for aluminum tank has a service life of about 20 years.

In reality, aluminum tanks by engineering can withstand the stress of 100000 refills or 10000 hydrostatic tests. In effect, this means the tank will last an enormously long time.

More practically, however, it really depends on the care and handling of cylinders. Near the ocean, the saltwater has the ability to accelerate corrosion. Large pressure and temperature changes can affect a tank’s lifespan. All this can reduce the tank’s lifespan.

Aluminum vs Steel

Aluminum tanks are more common in tropical waters where most recreational diving happens.

A modern and properly cared for steel tank lasts up to 50 years.

Considering the number above that sounds like less time. Steel tanks require more maintenance and are more susceptible to corrosive damage.

So, how do you make sure your tanks are safe? Always check your visual inspection and hydrostatic test dates fall within your dive date according to regional requirements.

The Visual Inspection

Every scuba diving tank requires a visual inspection annually. Trained technicians inspect the tank both inside and outside. They look for obvious dents in the material, very small cracks in the material, as well as corrosion. They also inspect the valve and use a snake camera featuring different imaging modes to clearly see the inside of the cylinder.

Once a tank passed its visual inspection it receives a sticker indicating the date of the inspection. Certified PADI, SSI or RAID divers then check this date prior to taking it on a dive.

The Hydrostatic Test

Hydrostatic tests require specialized equipment. This test is to ensure the integrity of the material.

Can this tank still withstand the pressure of refills?

In order to ensure this, technicians fill the tank to about 5/3 of its maximum capacity with water. Effectively overpressurizing the tank. During this time, the tank resides inside an armored tank filled with water to ensure the technicians’ safety.

Steel or aluminum at this extreme pressure will flex. The technician measures the amount of flex using the displacement of water around the tank. If successful, the tank resumes its original shape. If the metal is too fatigued and rips the cylinder fails its hydrostatic test.

Tanks that pass their test receive a stamp on the outside directly into the material. That way it is clearly visible to divers planning on using it.

Condemned tanks often serve as furniture and other creative fixtures in dive destinations.

Don’t Blow It

So when considering how many years does a scuba tank last, always remember to check your visual and hydrostatic test dates before accepting a tank for a dive. This is your responsibility as a certified diver. If you are considering purchasing a tank, always ensure that this tank has a good and documented history of visual inspections and hydrostatic tests. If I were to consider buying my own, I would pay a professional to take a look at the tank, basically doing an inspection right there and then.

Never Hold Your Breath. This is the most important rule in scuba diving. Beginner and certified divers learn this during their PADI, SSI, or RAID courses. They also learn the reasons why we should not hold our breath while diving. But what happens when you hold your breath while scuba diving?

What Happens When You Hold Your Breath While Scuba Diving?

When scuba divers descend, they expose themselves to additional pressure exerted on them by the water weight. This pressure affects how flexible air containers, such as your lungs, ears, and sinuses behave.

While a human lung can function under pressure and withstand shrinking by large percentages, it cannot expand much past 100%. When scuba divers take a breath at depth, their lung volume is 100%. This is due to the density of air at depth. The deeper, the denser air gets. Divers fit more physical air into their lungs at depth than what could fit on the surface.

Why Must Divers Exhale While Ascending?

A diver holding their breath during an ascent risks air not escaping naturally. Air volume in their lung expands due to less pressure at shallower depths. Air has to escape and the diver’s lung is forced to break.

This is a Lung Over Expansion Injury. The easiest way to prevent this injury is to continuously breathe in order to keep the lung volume at 100% regardless of the diver’s depth. This is different to decompression sickness or the bends.

Read more on what decompression sickness is and why it’s called the bends.

Can your lungs explode scuba diving? Not exactly. They can rip and tear, causing severe damage, but they generally won’t explode.

But Why Does This Happen?

The primary physics principle behind this is Boyle’s Law. Boyle’s Law dictates the linear relationship between a diver’s depth, therefore the pressure they are under and the correlating volume and density changes. The deeper a diver goes, the more pressure they are under. This means that flexible air containers shrink more and more. In order to keep lung volume at 100% volume, denser air fills the lung.

For example, at 20 meters depth, a diver is under 3 bar of pressure. That means the volume of air is at 1/3 and the density is 3 times what the same amount of air would be on the surface. In order to fill the lungs, this diver breathes 3 times the amount of air.

This directly relates to a diver’s air consumption. This is to say that air does not last as long deeper.

See how long a scuba tank lasts for more information on air consumption.

How to Breathe while Scuba Diving

So, now we know why it is important to never ever hold your breath while scuba diving, but is there a particular way we should breathe while diving?

Yes.

Ideally, we should be breathing calmly and slowly while scuba diving. This will relax the diver and reduce stress. As divers, we aim to have as much time as we can underwater. By breathing calmly, you will use less air from your tank, resulting in a longer duration dive. This is in comparison to breathing in and out rapidly and heavily.

Read More: How Long Does a Scuba Tank Last?

The best way to breathe while scuba diving is by allowing the exhale to be longer than the inhale. A classic parasympathetic (relaxed) breath is at about 1:1.5 ratio, for example; inhale for 4 seconds and exhale the same breath for 6 seconds.

What About Freedivers?

Freedivers hold their breath all the time when diving. In fact, that is how they conduct their dives. Will pressure affect them?

Actually, yes. Pressure changes affect free divers too. The biggest difference, however, is that they do not take a breath of compressed air at depth in order to equalize their lungs.

A freediver’s lung physically shrinks in size and rapidly expands on the ascent. Because these divers did not add additional physical amounts of air at depth, the remaining air volume in their lungs simply expands back to 100% by the time they reach the surface. The risk of lung overexpansion injury is therefore minimal.

This is why freedivers learn not to take a breath from a passing scuba diver and ascend holding their breath.

Can You Hold Your Breath Underwater?

Some of my students like to go down the line of asking why? and I really appreciate the curiosity. A junior diver I once taught said that this is only a problem if they were to hold their breath and ascend at the same time.

Very smart kid. That is correct. Because beginner divers might not have as much control over buoyancy and even ascent speed, it is safer to train them to never hold their breath. Furthermore, it is a mammal instinct that if you cannot breathe underwater the first instinct is to hold one’s breath and go up.

This could potentially be fatal.

The first thing I learned when I trained to become an Underwater Photography Instructor was that it is in fact a requirement in many circumstances to hold your breath in order to take a clear photo. Holding your breath limits body movement and keeps the camera nice and still. By that stage, however, I had very good buoyancy and breath control and knew not to even move a centimeter up or down while taking a photo.

I really enjoyed learning how to take pictures underwater with my friend Paddy. You can read more about his underwater photography career or learn how to become an underwater photographer yourself.

Let’s Take a Breath

Now that you know what happens when you hold your breath while scuba diving you can explain it to your curious friends. Maybe even inspire them to try out diving for themselves.