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The Scuba Diver’s Essential Kit

Scuba divers need plenty of kit to spend time underwater but some of it is specialised and isn’t required for every dive. In this blog we’re going to take a look at the essential bits of kit that every scuba diver should need for a dive and why.



This is the one piece of kit that separates us from snorkelling and free diving, and combined with your regulator becomes the Self Contained Underwater Breathing Apparatus that SCUBA stands for. Cylinders for diving are made from either steel or aluminium and have a working pressure of between 200 and 300 bar. Steel cylinders are heavier and less buoyant so we don’t need as much lead to sink and can contain higher pressures but they have round bottoms so usually require a boot and a painted coat to protect the steel from rusting.

Aluminium cylinders are lighter and more neutrally buoyant but tend to have lower working pressures around 207bar. Preferred by many divers because they are closer to neutrally buoyant Ali cylinders are easier to control.

The most popular size of cylinder is a 12 litre or S80 cylinder that gives you enough gas for around 1 hour of diving depending on depth and breathing rate. Larger 15L cylinders are the largest common size used for diving before twinning cylinders so you dive with two at once. Small cylinders are often used as redundant backups known as pony’s or stage cylinders.


Your Regulator regulates the high pressure from your cylinder down from the pressure inside the cylinder down to a much lower level that you can breathe from. The 1st stage does most of the work and is a demand valve that reduces the high pressure from the cylinder to around 8-10bar in the hoses that you breathe from so there is always plenty of air.

On the other end of the hoses are 2nd stages that are the mouthpieces that you breathe from and these are one-way demand valves that allow some of that 8-10bar out every time you breathe in and then the 1st stage takes more gas from the cylinder to replace it.

Most regulators on the market today are down-stream regulators and are designed so that even if something inside malfunctions the regulator will deliver gas if there’s still some in the cylinder. Regs will have a purge valve on each mouthpiece so you can fill the mouthpiece with fresh air and force any water inside out.


Your Buoyancy Control Device or BCD is the best way to stay neutrally buoyant so you neither float or sink in the water.  Connected to your regulator your BCD can be filled with air from your cylinder and dump valves on them allow you to get rid of gas inside.

BCDs are either Jacket or Wing shaped but work in a similar way. Jacket BCDs have sections that inflate around the waist whereas Wing style BCDs only inflate behind the diver. Most people start their training in a jacket style BCD but then move onto wings as they progress and buy their own kit.

Your BCD holds your cylinder onto your body and will have plenty of attachment points for gear. Some BCDs specialise or allow for different mounting options as you specialise with different diving techniques. Traditional BCDs are designed for a single back mounted cylinders but you can find specialised Sidemount BCDs and others made for Backmounted Twin Cylinders.

Weight System

 Both our body and most of our gear tends to float in water so scuba divers need some kind of weight to help us get down and stay down. We usually use lead blocks or shot to make us negatively buoyant and then use our BCD for minor corrections so we’re neutrally buoyant.

The downside to lead weight is that it only wants to make us sink so if there are any problems in the water we need a way to get rid of it quickly so on most weight systems they will have a quick release function so you can dump the lead and ensure you can float.

There are various ways to mount lead and the most traditional is a weight belt. Weight belts are either a simple 2″ webbing belt with a quick release buckle that you thread the lead onto or a more modern belt with pockets but the same QR buckle that you just need to tug to open.

Most BCDs today are fitted with integrated weight pockets so you can fit your lead in specialised pouches in your BCD and drop them with a quick tug on a handle if needed. By mounting your lead in integrated pouches the lead doesn’t sit on your hips so it’s more comfortable but it does make your scuba unit more heavy to carry around on the surface.

Dive Computer

Dive computers are eliminating the need of learning and using dive tables to make your diving safer and less complicated. Your dive computer consists of a stopwatch, a pressure sensor and algorithms inside all rolled into one little machine. A good dive computer will tell you how long you can stay at a certain depth, when to ascend, how fast you can ascend and when to perform a safety stop if necessary.

Some computers connect to various other sensors to tell you more about your diving. Many computers will connect to a wireless air transmitter that fits to your regulator and tells your computer how much air you have left and how long it will last based on your breathing rate. Some others connect to a heart rate monitor that tailors your dive profile based on how hard you’re working.

At depth your body is absorbing more gases from the air you breathe than normal. Before long an amount of Nitrogen dissolves into your tissues and this is what your computer is working out based on your depth, how long you’ve been there and the algorithm inside it that brings everything together and estimates how much Nitrogen is absorbed in your tissues.

Most places won’t let you dive with them if you don’t have a computer, which just goes to show how they have increased safety in diving. Choose a dive computer for the diving that you plan to do in the future because chances are you’ll only buy one or two computers, so you won’t want to be restricted in the future because your computer doesn’t have a certain feature.


Your mask is the window to the underwater world because our eyes aren’t designed to focus underwater, we need an air pocket in front of our eye to focus. Masks are usually the first piece of kit that you buy and will go with you for most of your diving career. Your mask needs to fit properly and be comfortable and once you have found one that you like then you need to spend some time preparing it so it doesn’t fog up during your dive.

Spend time trying your mask on and see how it fits and feels. You’re going to be wearing this thing on your face for an hour or so at a time so you don’t want it to be uncomfortable in any way. Clear skirts may let more light in but they can discolour over time especially if you leave them in the sun. Black skirts don’t discolour and they do focus your vision but some divers just prefer a clear skirt.


Fins are essential for propulsion because water is hard to move through and our arms and legs aren’t made to move us through water efficiently. Divers usually use Open-Heel fins with boots because they offer better comfort and efficiency.  Fins come in plenty of different shapes and colours and the different fin styles work in different but similar ways to direct water and move you through it.

Most fins today have a mix of two or more materials so the shape of the fin changes during each part of the fin kick so it traps water and directs it more efficiently. A lot of science and testing goes into fins, reducing drag in certain areas and improving energy transfer. Some designs are all-rounders and work with most fin kicks others have a limited range so splitfins don’t work effectively with a frog kick.


Exposure Protection

Water conducts heat away from your body much faster than air so even in warm feeling waters you will get cold before long and require a wetsuit or drysuit to stay warm especially the deeper you go.  Neoprene Wetsuits trap a layer of water against your body and use that and the small bubbles inside the material to insulate your body and keep you warm.

Thicker wetsuits keep you warmer in colder waters but for the coldest waters divers use Drysuits that trap a layer of air over your body that is a better insulator than water but requires more training to use properly. Covering your head and your hands helps a lot in cold water too so you feel more comfortable.


Knives and cutting tools are an essential piece of kit for most divers to free themselves from an entanglement. The oceans are full of fishing line and other tangling lines that can wrap around your gear and trap you under water. Fishing line is often hard to see and has high breaking strengths so must be cut to get free, so knives or cutting tools are essential and many divers are helping the environment by collecting tangled fishing ghost gear by cutting it free so other divers and marine life don’t get caught in it later.


Light doesn’t pass through water as well as air and the deeper your go the more red light is absorbed so torches are often carried by divers to see and be seen.  Enclosed areas like caves and wrecks require torches so you can see in the dark areas but many team divers use torches and their beam to communicate with other team divers too.

Safety Devices

Surface Marker Buoys or SMBs are used by divers and much like dive computers are becoming a required piece of kit for many divers because they mark your position on the surface and make you easier to spot by boats. Delayed Surface Marker Buoys, dSMBs, are carried by divers deflated and can be inflated by the diver so it floats to the surface to let nearby boats know that you are ascending shortly and give you space. Reels and Spools for sending up dSMBs can also be used to lay guidelines in overhead areas to find your way back out.

Unique Tools

Some diving requires unique tools such as drift hooks in areas of high current or lift bags for raising objects. Compasses are also useful for divers for navigation because it is easy to loose your way and sense of direction underwater. There are plenty of unique tools for certain situations so it’s best to do your research first and see what you might need wherever you’re diving.