When we think about scuba diving, we all have a certain image: a diver with a scuba tank on his back breathing air through u hose. But how does scuba diving actually work? How can we breath under water? To answer this question, we need to start at the beginning and ask ourselves what the term SCUBA diving stands for. Do you know?
What does SCUBA stand for?
To understand what scuba diving is, we need to know what SCUBA stands for. SCUBA is short for Self Contained Underwater Breathing Apparatus. When we dive, we need to enable ourselves to breath under water. For this, we need the scuba equipment.
Scuba equipment, or scuba gear, exists of different parts that all work together to enable you to scuba dive. Here we list the most important parts and what their function is:
- Scuba cylinder / scuba tank: contains the compressed gas that we breath. The standard gas is the same mixture of the air we breath above the surface: 21% oxygen and 79% nitrogen. It can however, also contain different gas mixes. Nitrox, or enriched air for example. This mix contains a higher percentage of oxygen and therefore a lower percentage nitrogen. This extents your allowed bottom times. More about this topic in another article. The gas inside the tank is compressed to a pressure of around 200bar. The tanks are made from aluminium or steal. Steal tanks are heavier under the water. Therefore you use less weight during your dive. However, steal tanks are more sensitive for corrosion. This is why a lot of divers prefer aluminium tanks. There are also different sizes available: 8liter, 10 liter, 12 liter or 15 liter. The 10liter tanks are mostly used by kids. The 15 liter tanks by people that use lots of air. The 12 liter tanks are the most common and are the standard size for most dive centers, also our diving center hurghada.
- Regulator: the regulator consists of two parts: the first stage and the second stage. The first stage lowers the pressure from the tank (200bar) to what we call middle pressure (a little higher pressure then the pressure surrounding you). The second stage has a mouthpiece connected to the end. When we breath through this mouthpiece, the second stage lowers the pressure from the first stage to the pressure equal to the pressure surrounding us. This enables you to breath.
- Submersible Pressure Gauge (SPG): the SPG shows how much pressure is left inside your tank. This way you can see how much air you have used during your dive and when it is time to turn back and end the dive before you run out of air.
- Low Pressure Inflator Hose (LPI): the LPI connects the air from your tank to your BCD. This way you can inflate and deflate your BCD to control your buoyancy.
- Buoyancy Control Device (BCD): your BCD is like a jacket and has multiple uses: it is 1 of 3 ways for you to control your buoyancy, it carries the tank on your back and can hold any accessories you wish to bring with you during your dive. There are countless types of BCD’s that all have different designs, shapes and sizes. It depends on the type of dives you are planning to do, your body type and of course comfort, which one is best for you. Therefore we advise you to always go to a professional shop so they can help you pick the best fit for you.
- Dive mask: a dive mask makes sure you don’t get water or dirt inside your eyes during the dive and enables you to see clearly under water. There are even prescription masks available now so that people who wear glasses above the water, can also see clear under water. Wearing contact lenses is no problem. You can keep them in while diving and use a standard dive mask. What is very important, is that the mask is a good fit. Not a single person has the exact same shape face. This is why there are countless models dive masks. We advise you to visit a professional and try out different brands to find your perfect fit.
- Fins: when you dive, you don’t use your arms to swim. You only use your legs. Wearing good fins helps you swim more easy. There is a difference in fins for snorkeling and diving. Diving fins are usually a lot stronger and also bigger and heavier than snorkeling fins. With diving you need to have more power from your fins to move easily through a current for example. There are a lot of different models and designs and all of them have a different purpose. There are heavy fins or lighter ones. Fins with an open back that you wear with boots, or with a closed, build in boot. So when you are looking for a new pair of fins, it is wise to have a professional help you pick the right ones for you.
- Dive computer: as a diver, you are limited in the amount of time you can spent under the water and the maximum depth you are allowed to dive at. Before there were dive computers, scuba divers used special dive tables to calculate how long and how deep they were allowed to dive. Nowadays we use dive computers for this. They do all the math for you. A big advantage is that dive computers are very accurate and reliable: they know exactly how long you have been at a certain depth and what the effect of this is on your body and also on your next dive. The dive computer will constantly calculate and adjust your limits, even during the dive. Another big advantage, is that your dive computer logs every dive for you. It keeps track of your maximum depth, dive time, temperature, dive profile, safety stops and some computers even track your air consumption. There are all kinds of dive computers on the market. One is even more exclusive than the other. When you look for a dive computer, make sure you don’t buy (and pay for) more than you need. When you just start diving, you do not need a dive computer that costs thousands of euro’s. You can start with a basic computer that shows you what you need. The prices start around 200eu. Have a professional help you pick out the best dive computer for you.
- Wetsuit/dry suit: in water, the human body cools down 20 times faster than above the water. So even when you are scuba diving in water of 27 degrees, you will start to feel cold at some point during the dive. This is why scuba divers wear wetsuits or drysuits. There are many types of wetsuits available. From 3mm shorties for tropical waters, to 7mm long wetsuits for water of 15-20 degrees. When you scuba dive in colder water, your will want to use a dry suit. A wetsuit keeps you warm by letting a small amount of water come inside. Your body warms this water and in return, the water will keep you warm. As you can see, it is important the wetsuit is tight enough and is a perfect fit. If not, the water will keep flowing in and out the suit and it will not keep you warm.
A dry suit doesn’t let any water come inside. Therefore it will keep you nice and warm. You do however need to take a dry suit course to learn how to dive with this. Because there is air inside the dry suit, you need to learn how to control your buoyancy during the dive and how to prevent a ‘squeez’ when the pressure during the dive effects the air inside the dry suit.
So you guessed it: when you are looking to buy a wetsuit or a dry suit, make sure to have a professional advise you so you buy the best suit for your diving plans.
Now you know the standard scuba dive gear. Ofcourse there are so many accessories available that could be of great use to you while scuba diving. For example: SMB, dive knife, shaker to make sound under the water, dive torch, compass etc. It is very important to start with a good base and work from there. Don’t get more than you need because you also need to carry it with you on your dive. In case you wish more advise or tips: you can always contact us through [email protected]
How deep can you scuba dive?
How deep you can scuba dive depends on the level you are certified to. There are different levels:
- Scuba diver: as scuba diver you are allowed to dive to a maximum depth of 12 meters
- Open water scuba diver: as an open water scuba diver you are allowed to dive to a maximum depth of 18 meters
- Advanced scuba diver: as an advanced scuba diver, you are allowed to dive to a maximum depth of 30 meters
- Deep specialty diver: after completing the deep specialty you are allowed to scuba dive to a maximum depth of 40 meters.
The absolute maximum depth you are allowed to scuba dive to as a recreational diver is 40 meters. It is possible to dive deeper than 40 meters, but you will need to change from recreational diving to technical diving. This is because at a certain dept, the air we breath will get toxic. So the air mixture we breath will need to change. As a technical diver, you will learn how to mix different types of gasses together to increase the maximum depth you are allowed to dive to. We will explain more about this topic further down in this article.
How deep can a human dive with scuba dive equipment?
Humans can dive as deep as 450 meters. However, this is not possible with normal scuba dive equipment. With scuba dive gear you are allowed to dive to a maximum of 40 meters. During scuba diving, you breath from a so called ‘open circuit’. This means that the air you breath out, is released in to the water (bubbles). Do you wish to dive deeper than 40 meters? Then you need special dive gear and switch to a ‘closed circuit’.
With a closed circuit, the air you breath out, is circulated back into the system, it goes through a filter and is re-used to breath. Therefore we call this system a ‘re-breather’. You can understand that you need special training to dive with a re-breather. You can follow this special training through a technical course or commercial course through our diving course hurghada.
To be able to dive beyond depths of 40 meter, you need to train to become a technical diver. As a technical trained diver, you are allowed to dive as deep as 100 meters. You will learn to dive with different air mixes and a closed circuit re-breather system (CCR). There are several levels of technical diving. Each level comes with a maximum depth and airmix. The levels are as follows (Padi): Tec40, Tec45, Tec50, Tec65 trimix, Tec40CCR, Tec60CCR, Tec100CCR.
Along recreational diving and technical diving, you have commercial diving. This is a very specialistic type of diving. Humans can dive to depths of 450 meter. These types of dives can not be done with regular scuba gear or a re-breather. Dives this deep, are done using special dive gear and usually the divers have air supplied to them from the surface, using a hose connected to their suits and helmets. They need these special suits and helmets to work under the immense pressure under the water. Here they perform duties like for example welding, building, cleaning, repairing etc. at oilrigs or other (off)shore sites. If you are intered into hurghada diving courses, you can also check our hurghada diving prices.
How deep was the deepest scuba dive ever recorded?
The deepest scuba dive ever recorded is 332,5 meter. Egyptian Ahmed Gabr, dove to this amazing depth using regular scuba equipment. The dive took place in the Red Sea, in front of the coast of Dahab, Egypt. It took Ahmed Gabr 12 minutes to scuba dive to the depth of 332,5 meter. The trip back to the surface, took him 15 hours. Why did it take Ahmed Gabr that long to ascend?
Why do you need to ascent slow after a scuba diving?
When you scuba dive, you will experience pressure of the water surrounding you. At the surface, we experience 1 bar pressure from the atmosphere around us. Every 10 meters we descend under the water, 1 bar of pressure us added. So at 10 meters depth, we experience 2 bars pressure. At 30 meters depth, we have 4 bars pressure. At 332,5 meter, Ahmed Gabr experienced a bizarre 33 bars of pressure!
So, what does this pressure do to your body? The air we breath consists of oxygen and nitrogen. Our body does not use nitrogen. At the surface, it is easy for our body to get rid of the unused nitrogen. However, under the water this is not as easy. Because our body is under pressure, it starts to absorb the nitrogen. The nitrogen forms small bubbles in our veins. This is harmless. When we return to the surface, the surrounding pressure drops back to 1 bar, and our body will again be able to get rid of the nitrogen in our bloodstream. The deeper you dive, the faster your body absorbs in the nitrogen. The longer you stay at depth, the more nitrogen your body absorbs.
Why is it so important to ascend as slow as possible after scuba diving? To make you understand, picture yourself a bottle of cola. If you shake the bottle and open the cap to fast, the cola will force itself out of the bottle and leave a big mess. But if you open the cap very carefully, and let the pressure release very slow, nothing will happen and the cola will stay inside the bottle without spilling a drop. Now, when you leave the bottle without the cap on it, after a while the bubbles will disappear from the cola.
The same principle goes for your body and nitrogen: when we ascent slowly, the surrounding pressure decreases slowly, allowing the nitrogen to dissolve gently and safely without harming our bodies. Do we shoot up to the surface after a dive? Then the nitrogen doesn’t have time to dissolve at a slow rate causing the small bubbles to form big bubbles. And this is what causes the trouble: big air bubbles traveling through your bloodstream. Trying to find a way out or ending up in places you do not want. This is what we call decompression sickness.
So now you understand why Ahmed Gabr took 15 hours to safely ascent from the deepest scuba dive ever recorded to 332,5 meters.
The deepest dive by human ever recorded
The deepest recorded dive a human ever made, was to a bizarre depth of 10.927 meter. Of course this was not done using (scuba) dive gear. The deepest dive ever was done using a specialy designed submarine. The person inside this submarine, was millionaire Victor Vescovo. He made the dive in the deepest part on the planet (as far as we know): the Mariana trench in the south part of the Pacific Ocean (east of the Philippines). Victor Vescovo spend an amazing 4 hours at 10.927 meters and even here, he saw a plastic back floating by. Both the descend and the ascent, took 3,5 hours each.
How deep can animals dive?
We now know how deep humans can (scuba) dive and what the deepest dives ever recorded are. But how deep can animals dive? Here is a fun list of a few animals that might surprise you with how deep they can dive:
Eel 8.370 meter
Octopus 7.000 meter
Cuvier’s beaked whale 2.925 meter
Elephant seal 2.388 meter
Sperm whale 2.250 meter
Manta ray 1.848 meter
Giant beaked whale 1.453 meter
Leatherback turtle 1.280 meter
Goblin shark 1.200 meter
Dolphin 1.019 meter
Seal 609 meter
Emperor pinguin 534 meter
How deep can humans dive without scuba gear?
Everybody tries to hold their breath sometimes and see how long you can hold it. There’s always that moment when you can’t hold it anymore and your body forces you to breath. There are people who train very hard to be able to hold their breath for a long time. They use this technique to dive without any scuba gear. We call this free diving.
What is free diving?
The name already says it: free diving, diving without any scuba equipment. During free diving you hold your breath. Using the proper techniques, you will be able to hold your breath under the water longer and longer. The pressure under the water helps you with this but also can be very dangerous. We will explain you more about free diving techniques in another article.
How long can you stay under water on one breath?
The average person can hold their breath for about 30 seconds. When you train on a regular basis, you can stretch this to around 10 minutes. Please do not try this without the proper training and supervision of professionals in this field. The record for longest breath hold / free dive, is set by Budimir Šobat. He held his breath for as long as 24 minutes and 37 seconds.
The record for deepest free dive ever recorded
Of course there is not only a record for deepest scuba dive ever or longest free dive ever. There is also a record for the deepest free dive ever. This record is on the name of Herbert Nitsch. Herbert made a free dive to a depth of an amazing 253 meters on a single breath.