How Scuba Diving Works

by Mihai Pinzariu on September 24, 2019

Scuba diving is one of mankind’s most amazing feats. We take the activity for granted these days – like it’s just a leisurely holiday adventure – but the fact that we have created an apparatus that allows humans to breathe underwater for extended amounts of time is simply incredible. Us mere mortals were designed for land, yet we’ve created a piece of equipment that lets us explore beyond the land to the depths of the sea. Yep… amazing. Without scuba diving, a lot of our oceans would have remained unexplored and undiscovered. We would never have been able to unearth incredible history from shipwrecks like the Titanic, or do amazing underwater work like install cables and pipelines. Much of the ocean’s creatures would have remained a mystery to us, and we would have had to enjoy tropical islands from the land only! If you’re curious how mankind managed to create such a piece of equipment that defies science, read on. We’re going to explain how scuba diving works, for the curious, the nervous, and the newbie!

How scuba works: in short

For the lazy, here’s a brief description of how scuba works. Scuba stands for self-contained underwater breathing apparatus, which essentially means a device that has all you need to breathe underwater. A scuba includes metal tanks which hold compressed air (or a special mix of breathing gases), a regulator to reduce the tank air pressure to breathable air, and a hose that carries the breathable air into the diver’s mouth. When a diver exhales, air is released into the water and creates little bubbles. To go scuba diving, you’ll also need other equipment like a dive mask, wetsuit, and buoyancy control device.

How scuba diving works

To understand how scuba diving works, we’ll look at the underwater environment, what equipment you will need, and how our bodies react when underwater. If you’re interested in taking up scuba diving (and who wouldn’t be), we’ll also talk about what you need to do to get started!

The underwater environment

Humans aren’t designed to be underwater, and it can be a hostile environment for people to go in (when they don’t have the right gear). Scuba diving equipment needs to tackle a number of underwater challenges, from breathing to temperature control, buoyancy, and visibility. Luckily, some amazing people out there have got to work and designed scuba diving gear that allows us to cope with all the risks of being underwater. Every piece of equipment is essential for scuba diving to happen safely. Let’s look at how scuba diving equipment works in more detail.

Scuba diving equipment

1. Wet or dry suits

The deeper you go underwater, the colder it gets. To stay warm, scuba divers need to wear insulating suits. This could either be a wetsuit or a drysuit. A wetsuit is designed to trap a thin layer of water between your body and the suit rubber. Your body will warm up the trapped water, and in turn it will keep your body warm. Wetsuits are designed to fit tightly on your body, and come in full-body lengths and short lengths that only cover your arms and torso. Drysuits, on the other hand, feature double-walled material with air insulation between the layers. Since air is a better insulator than water, drysuits tend to keep you warmer – you can also wear underwear with them for extra warmth! Drysuits tend to have tight fitting necks, wrists, and ankles to stop water from getting in. If you’re going seriously deep underwater, then you can also add accessories to your wet & drysuits, like hoods, gloves, boots, and vests.

2. Buoyancy control

Here’s where scuba diving starts to get a little tricky. When you’re underwater, you need to control how deep you are going. Generally, you will have a dive plan with predetermined levels planned for your adventure. To make sure you are able to control which depths you are diving, you will need to be able to control your buoyancy. Buoyancy is your body’s natural ability to float in the water. To make sure your body is able to stay below water – and not keep floating back up to the surface – you will need to control your buoyancy with a buoyancy control device (BCD – also sometimes called a buoyancy compensator [BC] or lead weights). A BCD is a backpack-type vest with a rubber bladder that can be filled with air to keep you floating at your ideal depth. You will also need to add additional weights to your BCD to help counter your wetsuit’s natural buoyancy. These can be placed in the pockets of your BCD or attached to a separate belt, depending on what’s more comfortable for you. Some newer BCDs come with built-in weights as well.

3. Scuba gas cylinders

Now, for the breathing! This is the part of scuba that scares people the most, so understanding how breathing works when scuba diving is a big part of easing your mind before heading out underwater. When scuba diving, you will typically breathe in either compressed air (78% nitrogen, 21% oxygen), or Nitrox (an oxygen-enriched combination of 64-68% nitrogen, 32-36% oxygen). This air will be held in aluminium cylinders that will be carried on your back while diving. Generally, the cylinders will weigh 14 kg when empty and hold around 3.2 kg of gas – enough to fill a phone booth!

4. Scuba regulator

So, you now have a gas cylinder full of compressed air. Unfortunately, you can’t breathe directly out of that cylinder as the high pressure would damage your lungs – so you need another piece of equipment. Your cylinder will be fitted with a regulator that converts the high-pressure oxygen into breathable air that you can take in on-demand. There are two stages to a regulator: The first stage attaches to the cylinder and converts high-pressure air into intermediate-pressure, and the second stage attaches to your mouth with a hose, converting the intermediate-pressure air into breathable air. You can read more about how scuba regulators work in our article here.

5. Diving mask

To protect your eyes from the underwater pressure, and to help you see all the amazing sea life, you’ll need to wear a mask that closes your nose and eyes from the water. You can get scuba diving masks in single or double face plates, and they are designed with stringent regulations to ensure safety and durability underwater.

6. Other scuba diving equipment

The equipment above is all you need to head out there and enjoy some fun scuba diving. If you’re looking to get more serious about your diving trips, though, you might want to invest in a few extra pieces of equipment to enhance your dives.

1. Gauges – To keep a close eye on your air pressure, depth, and location, divers can carry different gauges that clip onto your BCD. These could include a compass, pressure gauge for the gas cylinder, and a depth gauge.

2. Dive computer – This is a tiny computer worn on your wrist that can help you keep track of your depth and allowable bottom times. You can program your dive computer with your dive plan to help control your depths and times to make sure your scuba diving trip is going on track.

3. Fins – You could go finless, but on a scuba diving trip you’ll be easily exhausted! Fins will help you swim faster and easier, for smoother ascents and descents, and are a must on any diving trip.

4. Dive knife – Worried about getting tangled up in seagrass, coral, or pieces of your equipment? You can carry a dive knife to help cut yourself free from any underwater entanglements.

5. Slate board – Going diving with a friend? It can be lonely when you can’t talk underwater. Scuba divers like to use slate boards to communicate with each other, sort of like magna doodles that can be used underwater.

6. Dive light – The deeper you go underwater, the darker it gets. A dive light helps you see underwater, get a closer look at that tiny fish, or illuminate those mysterious night dives.

7. Safety float – Worried about boats passing over you while scuba diving? A safety float is designed to make divers visible from above the water’s surface and consists of a float with a line and dive flag. This helps warn passing boats and let them know that there are divers underwater.

How to get started scuba diving

Now you know how scuba diving works, and all the pieces of equipment that are required, you can see that it’s not as difficult as might appear! If you’d like to get into scuba diving, then the training involved will help ease any remaining worries or concerns and make sure you’re confident and comfortable before heading out underwater. You do want to be in fit physical condition before going for scuba diving training. Your equipment will weigh around 27 – 34 kg alone, and you want a healthy heart and lungs to be able to withstand the changing water pressure. If you feel physically up for it and are over 10 years old, then your first step will be to take an open water certification course by PADI or NAUI. A scuba diving open water certification course will teach you:

1. Introduction to scuba diving – although now that you’ve read this article, you should be well ahead of the class!

2. Training in diving physiology and the risks & hazards of diving, how to use scuba equipment & dive tables, creating a dive plan, and emergency procedures,

3. Practical training in all important dive skills like how to expel water from your dive masks, recover a regulator that’s fallen out of your mouth, do controlled emergency ascent, breathe from a friend’s air supply, and more.

As part of your training you will make at least four open-water dives before receiving your certification. After your open-water training you can advance to higher levels like rescue training, master training, instructor training, and dive master. And don’t think about heading out scuba diving without taking the open-water course… you won’t be able to rent or buy dive equipment without your certification card!

Scuba diving alternatives

Feel like this is all a bit too complicated, or lack the physical strength to take the open-water course? That doesn’t mean you have to miss out on the incredible scenery underwater. The world is still yours to explore with snorkelling, the easier, more comfortable version of diving. With snorkelling you’ll still get to enjoy an up-close and personal look at the diverse sea life, without having to strap on heavy equipment and take courses. It’s also a much calmer, safer, and more relaxing activity for those who aren’t physically fit. All you need is a snorkel mask, the ability to float, and off you go!

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