How Deep Can You Dive? Limits at Every Level

With an Open Water certification you can dive to 18 metres, the limit PADI and SSI both set for newly certified adult divers, while junior divers aged 10 and 11 are held to 12 metres. Advanced Open Water takes you to 30 metres, and a Deep Diver specialty to 40 metres, the generally accepted limit for recreational diving.

Those figures are training limits set by the agencies, but dive operators enforce them and Queensland builds them into its dive safety code. This guide sets out the limit at every level, why each one exists and what an operator will ask before a deep dive. It is general information: your instructor and your agency's current standards have the final say.

How Deep Can You Dive With Open Water Certification?

The answer is 18 metres. PADI says its Open Water Divers can dive anywhere in the world to 18 metres, and SSI gives the same recommended limit for its Open Water Divers. NAUI's entry-level course also keeps every open water dive within 18 metres.

There is a catch. PADI describes the limit as the depth you are trained to: 18 metres, or the deepest point of your training dives if you never reached 18. Course dives step down gradually, as our guide to the Open Water training dives explains, so ask your instructor how deep you actually went and log it.

PADI counts anything below 18 metres as a deep dive, so even 19 metres is outside an Open Water card. Juniors get lower limits, covered below, and a PADI Junior Open Water card converts to a full Open Water card at age 15.

Depth Limits at Every Level

| Level | PADI | SSI | |---|---|---| | Pool or confined-water try dive (from age 8) | Bubblemaker: 2 m | Try Scuba: 5 m | | Open water try dive, no certification | Discover Scuba Diving (from age 10): 6 m in the pool, 12 m on the optional open water dive | Not offered: Try Scuba stays in confined water | | Scuba Diver (partial certification) | 12 m, under a PADI professional's direct supervision | 12 m, with an SSI professional | | Junior Open Water, ages 10 and 11 | 12 m, with a PADI professional or a certified parent or guardian | 12 m, with a dive professional or a certified adult | | Junior Open Water, ages 12 to 14 | 18 m, with a certified adult | 18 m | | Open Water Diver | 18 m | 18 m | | Junior Advanced Open Water, ages 12 to 14 | 21 m | 21 m, after the deep adventure dive | | Advanced Open Water | 30 m | 30 m, after the deep adventure dive | | Deep specialty (from age 15) | 40 m | 40 m |

Past 40 metres you are into technical diving, which has its own courses, gases and equipment. SSI's Decompression Diving specialty, for example, still stops at 40 metres and no more than 15 minutes of decompression. For a wider view of the course ladder, see PADI course levels explained and our PADI vs SSI vs NAUI comparison. A Discover Scuba Diving session is the usual first taste.

What a Depth "Limit" Really Means

Agency limits are training standards, not laws. SSI's standards call them recommended depth limits and ask certified divers to stay at a depth that matches their training and experience. PADI's Standard Safe Diving Practices, which students sign, include limiting your maximum depth to your level of training and experience.

In practice they work as firm limits for three reasons:

- Local rules come first. PADI notes that local regulations override your certification, and that if a dive boat sets its own depth limit, you follow it. - Operators check. Charter boats look at your card, and often your logbook, before deeper sites. More on that below. - The physics does not read your card. The risks below grow with depth whatever you are certified for.

Why the Limits Exist

Nitrogen narcosis. Breathed under pressure, nitrogen acts like an intoxicant. Queensland's dive safety code says diving on air at or beyond 30 metres significantly increases the risk, and that narcosis affects reasoning, judgement, memory and coordination, then eases as you ascend. That is a large part of why Advanced Open Water stops at 30 metres. Our nitrogen narcosis guide covers the signs.

Gas consumption. Your regulator delivers air at the surrounding pressure, so every breath at depth takes more from the cylinder. SSI's course material puts it simply: at 10 metres (2 bar) you use twice your surface rate, and at 40 metres (5 bar) five times. DAN adds that deep dives drain gas much faster and often allow bottom times under 10 minutes, which leaves little margin for a problem.

No-decompression time. The deeper you go, the faster your body takes up nitrogen and the sooner you reach your no-decompression limit (NDL), the point past which you can no longer surface without stops. In the US Navy's air table the no-stop limit is about an hour at 18 metres, 25 minutes at 30 metres and about 10 minutes at 40 metres, and recreational computers allow less. Our NDL guide explains the details.

Help is further away. Queensland's code says dive workers breathing air should not be required to go beyond 40 metres, and tells operators to warn certified divers that if they get into difficulty below that depth, a worker may not be able to reach them.

Queensland's Rules

Queensland is the clearest Australian example of depth tied to certification. Its Safety in Recreational Water Activities Regulation 2024 governs dive operators: it requires a medical declaration before a try dive or a learn-to-dive course, limits an instructor to four uncertified divers at a time (six with a certified assistant), and makes operators log every diver's maximum depth. The regulation itself sets no depth limits.

Those sit in the Recreational Diving, Recreational Technical Diving and Snorkelling Code of Practice 2024, an approved code under the Safety in Recreational Water Activities Act 2011, in force since 1 August 2024. Under the code, operators should:

- keep uncertified try-dive participants at 12 metres or shallower; - keep students on an entry-level course within 18 metres, and children aged 10 and 11 within 12 metres; - advise certified divers not to go deeper than they are trained or experienced for; - assess each certified diver before the dive: when they last dived, when they were certified, their logged experience and their medical fitness, and if in doubt send an instructor along or run an assessment dive.

The code is written as "should" guidance, but it carries weight: courts can rely on it when deciding what was reasonably practicable, and following it is normally how an operator meets its legal safety duties.

What Operators Ask Before a Deep Dive

Expect some or all of these, wherever you dive:

- The right card. Yongala Dive, which runs day trips from Alva Beach in north Queensland to the SS Yongala wreck, requires Advanced Open Water. Open Water divers can only join by starting the course, doing a deep adventure dive with its instructor as the first dive of the trip. - Logged, recent experience. Yongala Dive asks for at least 10 dives on top of course training dives, may ask for logbook evidence, and wants a dive within the past 12 months, or a refresher with another shop first. Adelaide Scuba asks everyone on its ex-HMAS Hobart trips to have logged a dive in the past three months and to bring the logbook or other evidence. - A guide. Yongala Dive keeps Open Water divers in guided groups, and the Queensland code lets operators send an instructor with anyone whose competence is in doubt. - Extra cards. If you plan to dive nitrox, bring your nitrox certification too; Yongala Dive asks nitrox divers to upload theirs before the trip.

Carry your eCard, log every dive, and be honest about when you last dived. Our guide to your first 10 dives after certification covers building that logbook.

Australian Deep Sites by Level

These sites show how the levels work in practice. Check conditions, access and current operator rules before you go, and browse the full dive-site directory for more.

- Ex-HMAS Hobart, Yankalilla Bay, SA (Open Water and Advanced). The former destroyer sits in about 30 metres, with its highest structure about 5 metres below the surface. The National Parks and Wildlife Service code of conduct for the site gives an indicative guide: Open Water divers outside the wreck to 18 metres, Advanced divers outside to 30 metres, and going inside only with wreck or technical training. It also warns the wreck is not suited to inexperienced divers or anyone who has not dived for a while, and that qualified divers under 18 should dive with a qualified adult. - SS Yongala, off Alva Beach, Qld (Advanced). Yongala Dive describes it as an advanced site reaching 28 metres, with strong currents at depth. - Middle Ground, off Cronulla, NSW (Deep specialty). Michael McFadyen puts the top of this isolated reef at 28 to 29 metres and the sand at 31 to 33 metres, with a no-decompression time on air of about 16 or 17 minutes. His page notes no charter boats run there from Port Hacking, so it is a private-boat or club dive. - J2 submarine, outside Port Phillip Heads, Vic (Deep specialty). This First World War submarine lies in 31 to 39 metres, according to The Scuba Doctor. Lloyd Borrett rates it Advanced Open Water plus Deep, notes that a swim over the hull is mostly at about 33 metres and that it sits close to the shipping channel, and says the depth calls for experience, training, the right equipment and very careful planning.

Working Up to Deeper Dives

Depth is best added in steps. Build experience inside 18 metres first, then take Advanced Open Water, where the deep adventure dive is your first supervised trip past 18 metres. PADI's Deep Diver specialty adds four dives with an instructor covering descents, buoyancy, safety stops, gas planning and narcosis; SSI's version has three open water dives. Both require you to be at least 15.

On the dive itself, DAN suggests turning back with plenty of gas: use no more than a third of your supply on the way out and a third coming back, keeping the last third for the ascent, the safety stop and emergencies. Then ascend slowly and make your stop. To find a shop that runs these courses, start with the Sydney, Melbourne or Adelaide directories.

Your card sets how deep you are trained to go. Your experience, the conditions and how you feel on the day decide how deep you should go.

Sources

- PADI: Open Water Diver course - PADI: Advanced Open Water Diver course - PADI: Deep Diver specialty course - PADI: Discover Scuba Diving - PADI Blog: PADI Scuba Diving Restrictions - PADI Blog: Junior Open Water Diver vs. Open Water Diver - PADI Blog: PADI Certification Rules and Requirements - PADI Pros Blog: Standard Safe Diving Practices - SSI Training Standards: Training Environments and Depth Limits - SSI: Open Water Diver - SSI: Try Scuba - SSI: Advanced Open Water Diver - SSI: Deep Diving specialty - SSI: How Deep Can Scuba Divers Go? Scuba Diving Depth Limits Explained - SSI Training: course video transcript, Section 2 (air consumption at depth) - NAUI: Standards and Procedures 2026 (PDF) - Queensland Legislation: Safety in Recreational Water Activities Regulation 2024 - Queensland Legislation: Safety in Recreational Water Activities (Code of Practice) Notice 2022 - WorkSafe Queensland: Recreational Diving, Recreational Technical Diving and Snorkelling Code of Practice 2024 (PDF, worksafe.qld.gov.au; the site blocks automated checks) - DAN: The Depth of the Matter (Alert Diver, 2011) - US Navy (NAVSEA): U.S. Navy Diving Manual, Revision 7, Table 9-7 (public-release copy hosted by Arizona State University) - South Australia Marine Parks: Diving the HMAS Hobart - National Parks and Wildlife Service SA: Ex-HMAS Hobart Dive Site Code of Conduct (PDF) - Yongala Dive: Who Can Dive the Yongala - Yongala Dive: Frequently Asked Questions - Adelaide Scuba: Ex-HMAS Hobart - Michael McFadyen's Scuba Diving: Middle Ground - Lloyd Borrett: J2 Submarine dive site - The Scuba Doctor: J Class Submarine Wreck Dives (scubadoctor.com.au; the site blocks automated checks)

Header photo: A diver looks through the encrusted main anchor fitting of the ex-HMAS Hobart wreck in Yankalilla Bay, South Australia, by marv4mart, CC BY 2.0, via Wikimedia Commons.