What Is Scuba Diving? A Beginner's Overview

You've seen the photos: coral gardens, sea turtles, walls of colour. This guide explains what scuba diving actually is, how it works, and what to expect as a complete beginner in Australia. It is general information; questions about your own health or fitness to dive belong with a doctor trained in diving medicine.

What scuba diving actually is

Scuba diving is a form of underwater diving in which you carry your own breathing gas supply, freeing you from any connection to the surface. The word SCUBA stands for Self-Contained Underwater Breathing Apparatus.

Unlike snorkelling, where you remain at the surface and hold your breath to go under, scuba diving lets you breathe normally while fully submerged. A compressed air tank on your back, combined with a regulator that delivers air on demand, means you can stay underwater for 30 to 60 minutes at a time, exploring at depth without rushing back up to breathe.

Unlike freediving, where you descend on a single held breath, scuba requires no breath-holding at all. You breathe continuously, just as you would on land. This makes it accessible to most people, including those who find the thought of holding their breath underwater daunting. You do need to be able to swim, but not fast (see the swimming question below).

Good to know: comfort in the water and a willingness to learn matter more than athletic ability, but you do need a reasonable base of fitness: the standard diver medical questionnaire uses walking 1.6 km in 14 minutes, or swimming 200 metres without a rest, as its example of moderate exercise. There is no upper age limit as long as you meet the medical standards, says SPUMS (the South Pacific Underwater Medicine Society).

How scuba diving works

The physics of diving comes down to pressure. The deeper you go, the greater the water pressure around you. Your body, mostly liquid, handles this well, but the air spaces in your ears, sinuses and mask need equalising as you descend, much like your ears on a plane. Your lungs look after themselves as long as you keep breathing normally.

Your equipment does most of the heavy lifting:

- A cylinder (tank) holds compressed air at around 200 bar, roughly 200 times atmospheric pressure. - A first stage regulator attaches to the tank and reduces that pressure to an intermediate pressure, usually about 8 to 11 bar above ambient (the pressure of the surrounding water at your current depth). - A second stage regulator, the mouthpiece you breathe from, delivers air at the pressure of the surrounding water, only when you inhale, and vents your exhaled breath as a stream of bubbles. - A BCD (buoyancy control device) lets you add or release air to hover neutrally at any depth, rather than constantly swimming up or down.

Breathing underwater feels surprisingly natural after a few minutes, and most beginners are soon so absorbed by what they're seeing that they forget to think about it.

The golden rule: Never hold your breath while ascending. As you rise, the air in your lungs expands with decreasing pressure. Breathing continuously, and ascending slowly, allows that air to escape safely. This is the most important rule in scuba diving, and it's the first thing every instructor teaches.

The essential gear

Most learner divers use hire equipment provided by their dive school or operator. Once you're certified, the usual first buys are a mask, snorkel, boots and fins, because they are cheap and fit matters most for them; a dive computer usually comes next. A full set of personal gear can follow as you dive more regularly.

Mask

- Creates an air space so your eyes can focus underwater. Fit and a good seal are everything, a leaking mask is miserable.

Fins

- Power your movement through the water with minimal effort. Proper finning technique is more important than fin size.

Wetsuit

- Keeps you warm mainly through the tiny gas bubbles in its neoprene foam; the thin layer of water inside the suit adds little. Thickness depends on water temperature: a 3mm suit covers tropical Queensland for most divers, Sydney divers mostly wear 5mm, and Victoria, South Australia and Tasmania call for 7mm or a semi-dry in winter. Our wetsuit thickness guide has the detail.

BCD

- A jacket that holds your tank and lets you fine-tune your buoyancy by inflating or deflating an internal bladder.

Regulator

- The breathing assembly connected to your tank. Includes the first stage, second stage (mouthpiece), and an alternate air source for emergencies.

Dive computer

- Tracks your depth, time, and ascent rate in real time, calculating how long you can safely stay at depth. Essential for every dive.

Cylinder

- The tank of compressed air strapped to your BCD. Usually aluminium or steel, with working pressures of roughly 184 to 300 bar (232 bar is a common rating). In Australia every cylinder must be inspected and tested every 12 months before a shop will fill it.

Weight system

- Small lead weights on a belt or integrated into your BCD to offset your natural buoyancy and the buoyancy of your wetsuit.

A complete personal kit typically costs roughly $2,000 to $4,000, before extras such as a hood, gloves, torch or surface marker buoy. What Scuba Gear to Buy First sets out what to buy in what order, and our gear reviews cover tested options at every price point.

What to expect on your first dive

Your first experience of being underwater with scuba gear is genuinely unlike anything else. Most people describe a feeling of weightlessness, profound quiet, and, once the initial excitement settles, a kind of calm that is hard to find on land.

Before you enter the water

Your instructor or divemaster will brief you on the dive site: the maximum depth, the planned route, the hand signals you'll use to communicate, and what to do if something doesn't feel right. Never enter the water without a briefing, no matter how experienced you become.

Descending

The first metre is always the most disorienting. You deflate your BCD, begin to sink, and the surface recedes above you. Your ears will need equalising: pinch your nose gently and blow, just as you would on a plane. Do it early and often on the way down, before you feel any discomfort. If it hurts, stop, ascend slightly and try again. Never force it. Our equalisation guide covers the techniques.

Underwater

Once you're at depth and neutrally buoyant, the experience opens up. You'll communicate with hand signals, OK (forming a circle with thumb and forefinger), something's wrong (flat hand rocking side to side), going up or down (thumbs up or down). You'll be amazed how much expression you can convey without words.

Ascending

You'll ascend slowly, no faster than about 9 metres a minute (the rate DAN, the Divers Alert Network, recommends; training agencies set limits between 9 and 18 metres a minute), and make a three-minute safety stop at about 5 metres before surfacing. Research cited by PADI found fewer bubbles in divers who made a safety stop. It becomes automatic after a few dives.

First dive tip: Buoyancy control, hovering motionless in the water, is the skill that separates comfortable divers from anxious ones. It takes a few dives to master, and that's completely normal. Don't be hard on yourself if your first dive involves a lot of up-and-down movement. It settles.

Types of diving in Australia

Australia's varied geography means the type of diving on offer differs dramatically by location. Understanding the main styles helps you choose where to start.

| Type | What it involves | Best for | Level | | --- | --- | --- | --- | | Reef diving | Exploring coral or rock reef structures, typically 10 to 30m | Marine life encounters, colour, photography | Beginner | | Shore diving | Entering from a beach or jetty, no boat required | Low cost, flexible, local exploration | Beginner | | Boat diving | Accessing offshore sites by dive boat, often moored over a site | Deeper reefs, offshore visibility, variety | Beginner | | Wreck diving | Exploring sunken ships, aircraft, or artificial structures | History and photography; going inside a wreck needs wreck or technical training | Intermediate | | Drift diving | Moving with the current rather than fighting it | Covering distance, seeing pelagic life | Intermediate | | Night diving | Diving after dark with a torch, revealing nocturnal behaviour | Octopus, crustaceans, bioluminescence | Intermediate | | Liveaboard | Multi-day trips on a dive vessel with several dives a day | Remote reefs, Coral Sea, intensive experience | All levels: some Cairns Open Water courses train on one, while remote trips may ask for logged dives |

What you'll see underwater in Australia

Australia has one of the most biodiverse marine environments on Earth. With almost 60,000 kilometres of coastline once its islands are counted, the range of species you can encounter is extraordinary, and it changes dramatically from one state to the next.

Commonly encountered species around Australia

- Green and loggerhead sea turtles - Wobbegong and reef sharks - Weedy and leafy sea dragons - Giant cuttlefish (SA aggregations) - Manta rays (Coral Sea, offshore Queensland) - Moray and zebra eels - Potato cod (Cod Hole, Ribbon Reefs) - Nudibranchs and flatworms - Frogfish and scorpionfish - Schools of fusiliers and trevally - Octopus and blue-ringed octopus - Leopard sharks and grey nurse sharks

The Great Barrier Reef is the obvious flagship: the world's largest coral reef ecosystem, protected by a marine park that stretches about 2,300 kilometres along the Queensland coast. But the temperate waters of Victoria and South Australia offer encounters you simply can't find in the tropics: giant Australian cuttlefish, leafy sea dragons, fur seals and historic wrecks.

Browse our dive sites to explore what's on offer in every state and territory.

Is scuba diving safe?

Serious accidents are uncommon when divers stay within their training and limits, but diving does carry real risks. Health matters: SPUMS reports that 28 per cent of recreational diving deaths have a cardiac event as the disabling injury, which is one reason the medical questionnaire exists.

The most common beginner concern, running out of air, is addressed directly in your Open Water course. You learn to monitor your gauge throughout every dive and to signal your buddy when your air reaches a reserve level. As long as you stay within your no-decompression limits, which your dive computer tracks, you can make a slow, direct ascent to the surface with a safety stop. Stay too deep for too long and mandatory decompression stops come into play, which is beyond recreational training: see No-Decompression Limit (NDL): What It Means.

The risks associated with diving are well understood and very manageable:

- Decompression sickness (DCS): nitrogen absorbed at depth forms bubbles in the body as the pressure drops, most often after ascending too fast or staying too deep for too long. The risk is kept low by ascending slowly and staying within the no-decompression limits on your dive computer, although DAN notes that bubbles can form even within accepted limits. Our decompression sickness guide covers the symptoms and first aid. - Ear barotrauma: discomfort or injury from not equalising on descent. DAN calls middle-ear barotrauma the most common dive injury. Don't dive with a cold or congestion, never force equalisation, and ascend slightly if the technique isn't working. - Arterial gas embolism: Caused by holding your breath and ascending. Prevented by the most basic rule of scuba diving: always breathe continuously. - Marine life encounters: Australia's waters contain dangerous species, including blue-ringed octopus, cone shells, and stonefish. Your instructor will cover what to look for and, most importantly, the rule that prevents most injuries: look, don't touch.

Medical requirements: before any course you fill in the Diver Medical Participant Questionnaire. If you can answer no to all ten questions, you do not need a doctor. Some yes answers, covering things such as heart and lung problems, epilepsy, diabetes, recent surgery and prescription medicines, mean you need a doctor's evaluation before you dive, ideally from a doctor trained in diving medicine. Our guide to scuba diving medicals explains what usually matters.

Do you need a licence to scuba dive?

You do not need a licence to try scuba diving, but you need one to dive independently. A Discover Scuba Diving experience (also called an intro dive or try dive) lets you experience scuba under an instructor's direct supervision without any prior training. These sessions are available at dive operators across Australia, and many people's first underwater experience is exactly this: see Discover Scuba Diving: Try Before You Commit.

To dive without a supervising instructor, to hire tanks, join boat dives, dive at sites independently, you need an internationally recognised certification card. The standard entry-level qualification is the PADI Open Water Diver (or SSI equivalent), which authorises you to dive to 18 metres with a buddy.

| Certification | Maximum depth | Prerequisites | | --- | --- | --- | | Discover Scuba (try dive) | 12m under instructor supervision | None; minimum age 10 with PADI, 12 for try dives in Queensland | | PADI / SSI Open Water | 18m with a certified buddy | Minimum age 10 (Junior Open Water to 14, full card at 15); swim test | | Advanced Open Water | 30m (21m for 12 to 14-year-olds) | Open Water certification; minimum age 12 | | Rescue Diver | No depth increase | PADI Adventure Diver with the navigation dive, or Advanced Open Water, plus CPR and first aid training within 24 months; minimum age 12 | | Divemaster | Professional rating to guide other divers | Rescue Diver, first aid training within 24 months, 40 logged dives and a doctor's medical clearance within 12 months; minimum age 18 |

For the full ladder, read PADI Course Levels Explained, and for time and money see How Long Does It Take to Get Scuba Certified and How Much Does It Cost to Get Scuba Certified.

Common questions about scuba diving

Can I scuba dive if I'm not a strong swimmer?

You need to be comfortable in water, but you don't need to be a strong swimmer. PADI's Open Water course asks you to swim 200 metres without stopping (or 300 metres with mask, fins and snorkel), any stroke and with no time limit, and to float or tread water for 10 minutes. Australian SSI centres list a similar 200 metre swim and 10 minute float, while NAUI asks for more, including a 412 metre snorkel swim. Our fitness guide covers how to prepare.

How deep do you dive?

Open Water certified divers are trained to a maximum of 18 metres. Advanced Open Water extends this to 30 metres. Recreational diving in general stays above 40 metres, beyond that is the domain of technical diving, which requires specialist training and equipment.

Many of the shore sites beginners use are much shallower: Pro Dive puts Camp Cove in Sydney at about 8 metres and Gordons Bay at about 14 metres.

Can I fly after scuba diving?

Not immediately. DAN recommends a minimum surface interval of 12 hours before flying after a single no-decompression dive, 18 hours after multiple dives in a day or several days of diving, and substantially longer than 18 hours after any dive that needed decompression stops. Queensland's code of practice for dive operators is stricter, at 24 hours or more after multiple dives in a day, several days of diving or a decompression dive, and reef operators such as Sunlover ask for 24 hours after more than one dive. The reason is pressure: an airliner cabin can be at the equivalent of 8,000 feet (about 2,400 metres), and DAN explains that any bubbles in your body expand by about a third at that pressure while more nitrogen diffuses into them. These are minimums, so build a buffer into your trip.

What's the minimum age for scuba diving?

PADI and SSI let children start Open Water from age 10. Divers aged 10 to 14 earn a Junior Open Water card, with tighter limits: 10 and 11-year-olds dive no deeper than 12 metres with a dive professional or a certified parent or guardian, and 12 to 14-year-olds no deeper than 18 metres with a certified adult. The card becomes a standard Open Water card at 15. PADI's Discover Scuba Diving also starts at 10, but Queensland's code of practice sets 12 as the minimum for try dives, and many shops set their own higher minimums. At the other end, SPUMS says there is no upper age limit as long as you meet the medical standards, with regular medicals recommended from 45.

How long does a dive last?

A typical recreational dive lasts between 30 and 60 minutes, depending on your depth and air consumption. Deeper dives are shorter, the deeper you go, the faster you breathe through your air supply. Beginners tend to consume air faster than experienced divers due to breathing more rapidly from excitement or effort, so early dives are often closer to 30 to 40 minutes.

Is scuba diving expensive?

In Sydney an Open Water course costs about $595 to $895, usually with eLearning and hire gear included, while a Great Barrier Reef course from Cairns costs about $900 to $1,480 depending on how many nights you spend on the reef. Once you're certified, a single dive costs from about $70 before gear hire: Perth Diving Academy charges $70 for a boat dive plus $85 for full gear hire, and Diving Adelaide charges $199 for a guided double shore dive at Port Noarlunga. Owning your own gear is the bigger investment, though beginners usually start with a mask, snorkel, boots and fins. Our guides to certification costs and ongoing diving costs have the detail.

Ready to take the plunge?

Start with Is Scuba Diving Right for Me?, try a Discover Scuba Diving session, or work through the rest of our Learn to Dive hub.

Sources

- Wikipedia: Scuba diving - Wikipedia: Diving regulator - Wikipedia: Diving cylinder - Wikipedia: Wetsuit - DAN: DIN Connectors Are No Yoke - WorkSafe Victoria: Explosion during the filling of scuba cylinders - UHMS and Diver Medical Screen Committee: Diver Medical Participant Questionnaire (2026) - SPUMS: The SPUMS diving medical, 6th edition 2025 (PDF) - DAN: Middle-Ear Barotrauma (MEBT) - DAN: The Depth of the Matter - PADI Pros: Standard Safe Diving Practices - PADI Blog: History of the Safety Stop - NAUI: Standards and Policies Manual, 2026 edition, version 2.0 - US Navy Diving Manual, Revision 7 (PDF) - DAN: Decompression Illness - DAN: Flying After Diving - DAN: Altitude and Decompression Sickness - WorkSafe Queensland: Recreational Diving, Recreational Technical Diving and Snorkelling Code of Practice 2024 (PDF, worksafe.qld.gov.au; the site blocks automated checks) - Queensland Legislation: Safety in Recreational Water Activities Regulation 2024 - Sunlover Reef Cruises: Introductory Scuba Dive - Geoscience Australia: Border Lengths, States and Territories - Great Barrier Reef Marine Park Authority: Reef facts - National Parks and Wildlife Service SA: Ex-HMAS Hobart code of conduct (PDF) - Pro Dive Cairns: 5 Day Learn to Dive Open Water Course - Spirit of Freedom: 3 Night Cod Hole and Ribbon Reefs Trip - PADI: Open Water Diver course - PADI: Discover Scuba Diving - PADI: Advanced Open Water Diver course - PADI: Rescue Diver course - PADI: Divemaster course - PADI Blog: PADI diving restrictions - SSI: Open Water Diver - SSI: The Scuba Dive Shop aka The Scuba Doctor, Rye (course listing) - Pro Dive: Camp Cove dive site - Pro Dive: Gordons Bay dive site - Frog Dive: PADI Open Water Diver Course - Dive Centre Manly: PADI Open Water Course - Divers Den: Beginner Dive Courses - Perth Diving Academy: Want to go diving? - Diving Adelaide: Port Noarlunga Reef and Jetty

Header photo: A diver finning over the wreck of the Cheynes III at Michaelmas Island in King George Sound, Western Australia, by Peter Southwood, CC BY-SA 3.0, via Wikimedia Commons.