10 Crucial Scuba Diving Facts Every Diver Should Know in 2024

Rok Valencic

There are over 1 million newly certified scuba divers every year who can’t possibly remember all the important things about scuba diving off the bat. Then, there are millions of seasoned divers who keep forgetting these crucial scuba diving facts, which are…well…crucial for safe and enjoyable diving.

I’m also one of them. Might as well be honest.

That’s why I decided to put together this list of the most vital facts about scuba diving that should serve as a refreshment mental note for every recreational scuba diver.

If you keep these in mind and stay mindful of others and the beautiful underwater world you’re entering as the exemplary diver I’m confident you are, you should be fine on your dives.

What Are the Scuba Diving Facts?

I’ve always known and understood some of these facts about scuba diving because I have a degree in physics, and my brain knows no other way (#braggingmuch), but some facts required quite a bit of research and calculation on my behalf.

Let’s go!

1. You Burn 300-600 kCal per Hour While Diving

Scuba diving kCal per day

I was surprised by this number; I didn’t think it was that high.

For example, this is about the same range as most people burn by running for an hour.

Many people think that body temperature regulation is the main source of energy consumption during scuba diving, but that is false.

Only about 30-90 kCal comes from thermal regulation.

Most calories (300-500) come from the simple fact that you’re moving. The fact that water resists every move you make makes a significant contribution.

2. You Need to Go 200 Ft Deep or More to Lose Natural Visibility

Visible light by water depth

At 200 feet or more, there is typically little to no natural visible light. It is nearly impossible for the human eye to see at these depths without artificial light sources.

This is because most light is reflected out of the water or absorbed by the time it reaches 200 feet.

At around 100 ft, known as the “twilight zone,” some colors are mostly lost, and everything appears in shades of blue.

This applies to clear waters during the day. In some areas, sediment or plankton can reduce visibility even in shallower depths.

Fun Fact
Water absorbs light really well, especially in the red part of the spectrum. That’s why water appears blue.

3. There Is Only One Ear Equalization Method That Doesn’t Involve Nose-Pinching

Voluntary tubal opening

And that equalization method is called the voluntary tubal opening.

It requires conscious control of upper throat muscles and the soft palate to open Eustachian tubes and equalize pressure.

If you want to learn voluntary tubal opening for a hands-free diving experience, follow my guide, where I’ll show you exactly how I learned it.

Scuba divers can also equalize just by swallowing, which doesn’t require pinching their nose either, but it isn’t as effective.

4. A Scuba Tank Can Become a Lethal Projectile Missile

Scuba tank projectile missile

Scuba diving tanks are filled with air at a pressure of about 3,000 psi.

If a tank is standing up and then tips over, the valve can break or be damaged, releasing air with such force that it turns the tank into a projectile missile.

This was one of the first things I learned from my scuba diving instructors back in the day, and trust me, you don’t want to play with it.

When the tank isn’t on your back, keep it safely between your legs if you’re seated, put it down on its side so it can’t roll away, or make sure it’s strapped in somewhere (especially if you’re on a boat!).

For comparison, a pneumatic nail gun launches nails at about 100 psi.

5. An Average Scuba Diver Wears 60-100 Pounds of Equipment

Scuba diving gear weight

Or about 30-45 kg.

This includes the entire scuba gear: BCD, regulator, wetsuit, tank, weights, mask, and fins.

If this sounds scary, don’t worry; you won’t feel any of it once you enter the water because buoyancy takes care of all the weight (including your own).

In comparison, skydiving and paragliding typically include 30-50 pounds of equipment. American football players wear 20-30 pounds of gear, similar to ice hockey players.

6. There Are More than 160 Different Recreational Scuba Diving Certification Agencies

Over 160 scuba diving certification agencies with PADI on top

You can get your diving certification almost anywhere in the world.

Although the list keeps changing, there are over 160 different scuba diving agencies offering certification for recreational divers worldwide, just over 20 in the USA alone.

Plus, this doesn’t include technical diving certification agencies, commercial diving, or those that specialize specifically in freediving or snorkeling.

By far, the most popular organization worldwide is PADI. It has the most active scuba divers and the most popular scuba diving program, the Open Water Diver.

7. The Most Common Diving Safety Risk Is Ear Barotrauma

Ear barotrauma in scuba diving

Ear barotrauma is damage to your middle ear. It affects over 40% of all divers at some point in their life.

It can happen when the difference in pressure between the middle ear and the environment is large enough, such as during descent.

Symptoms can include ear pain, hearing loss, ringing in the ears, and, in severe cases, ruptured eardrums.

But don’t freak out just yet. It’s likely that you’ve experienced it already and don’t even remember.

I remember snorkeling once as a kid and making a dive of about 8 feet. I didn’t equalize at all, and while it was a bit unpleasant at the bottom, it didn’t hurt that bad.

But the inside of my ear felt slightly uncomfortable the rest of the day. That was ear barotrauma. I was better the next day.

This is why equalization is so essential when scuba diving. Equalize early and frequently!

8. Only 0.0005% of Dives Are Fatal

Odds of scuba dive being fatal compared to some other causes

Out of approximately 30 million dives performed yearly, about 100-200 dives are fatal.

To give you an idea, you have a 0.2% chance of being hit by a car when you walk out on the street in the US, according to the National Safety Council.

The most common reasons for fatal dives are

  • Drowning (the leading cause of death among divers)
  • Arterial Gas Embolism (AGE): AGE occurs when air bubbles enter the bloodstream and travel to the arteries, potentially blocking blood flow to vital organs. This can happen due to rapid ascent without proper decompression, lung overexpansion injuries, or pulmonary barotrauma.

Unfortunately, these things occur primarily due to inexperienced divers going too deep, staying below too long, not following decompression stops, exceeding dive limits, or diving despite having medical conditions.

Get certified, dive within your certification limits, maintain your equipment regularly (and use a good dive computer!!), dive with a buddy, and you’ll be enjoying diving well into your retirement 🙂

If you’re a beginner diver, using a dive computer is highly recommended because it will help you keep track of your depth and safety stops. Any of the best beginner dive computers will do the job.

Fun Story
Some claim that coconuts kill the most divers annually. While this makes a fun story, it’s a myth. Some researchers compared what kills most people, sharks or coconuts, and apparently, it is coconuts in this case (?!), but this has very little to do with divers.

9. Holding Your Breath at 30 Ft and Ascending 10 Ft Can Overexpand Your Lungs by 17%

Lung overexpansion due to holding breath while diving

The air in your lungs expands as you ascend. If you hold your breath, the air has no clear escape path, and it will expand your lungs.

This can cause serious damage to your lungs and can be life-threatening.

Some training materials state that as little as a 2-foot ascent or descent with a held breath can lead to lung overexpansion injuries or arterial gas embolism.

This is why the golden rule of scuba diving is never to hold your breath.

10. 30-50% of Divers Experience the Martini Effect at Depths of 100 Feet or More

Scuba diving martini effect

As you descend deeper, you may experience nitrogen narcosis, often described as feeling “drunk” underwater.

This altered state of consciousness can impair judgment and motor skills, making it crucial to ascend to shallower depths to alleviate symptoms.

Under pressure, nitrogen becomes more soluble in the body’s tissues, including the brain. This means more nitrogen is absorbed into the bloodstream and delivered to the brain.

As nitrogen levels increase in the brain, it can lead to a slowing down of neural processes.

The effects of nitrogen narcosis are often compared to the effects of alcohol intoxication. You can experience a sensation of being “drunk” or “tipsy,” hence the term “Martini effect.”

11. Every Third Person Is Highly Susceptible to Seasickness

Seasickness in scuba diving

About one third of the world’s population is highly susceptible to motion sickness, where 80% of these fall into the medium-to-severe case of motion sickness.

Because most dive sites require a boat ride to reach them, a lot of divers get seasick while scuba diving.

And seasickness is just one of the forms of motion sickness. Luckily, there is also always a solution, although every diver needs some trial and error to find their own.

3 More Scuba Diving Facts Just For Fun

If you ever feel the need for a challenge, here are three world records set by scuba divers:

1. It’s Perfectly Doable to Scuba Dive at the Age of 100

World's oldest scuba diver William Lambert

The current world record holder for the oldest scuba diver in the world is William Lambert from the USA.

He set the record in 2020 when he was just over 100 years old – talk about a seasoned diver!

The oldest female diver is Jane Rhodes Martin from Mexico, who set the record in 2020 when she was just a day short of being 95!

The oldest diving instructor is Armando Torrigiotti from Italy, currently 91 years old. If most of that age is diving experience, that makes one badass instructor! 🙂

2. The Deepest Scuba Dive So Far Has Been 1,090 Ft 4.5 in (332.35 m)

Deepest Scuba Dive Record holder Ahmed Gabr

The world record was set by Ahmed Gabr from Egypt in the Red Sea in 2014.

Because Why Not..
The deepest dive by a dog was 13 feet (4 m). A dog called Shadow set the record in 2002.

3. The Longest Scuba Dive Lasted Over 8 Days!

Longest scuba dive record holder Cem Karabay

To be precise, his time underwater was exactly 192 hours, 19 minutes, and 19 seconds.

Cem Karabay set the longest dive record in a pool in Istanbul in 2011.

He also ate, drank, got massages, and played games underwater.

… I don’t know what to say.

Wrapping Up Scuba Diving Facts

There you go!

I hope these facts about scuba diving were a refreshing reminder of how exciting scuba diving can be and how vastly different underwater conditions are from what we’re used to on the surface.

Feel free to share these scuba diving facts with your diving buddies and your dive community.

Happy diving!

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.


The golden rule of scuba diving is never to hold your breath. Holding your breath and ascending or descending can overexpand or collapse your lungs, which can even result in death.

The rule of thirds in diving applies to dividing your air supply into thirds for safety and better distribution. One-third is used for the outward journey, one-third on the way back, and one-third is a safety reserve.

The word ‘scuba’ stands for Self-Contained Underwater Breathing Apparatus. In other words, scuba is the equipment you take to a dive that allows you to breathe underwater.