Advanced Open Water: the dives, the depth limit and the theory
In short
Advanced Open Water is five training dives: deep and underwater navigation, plus three you choose. With PADI, you can start at 12; adults are then certified to 30 m (100 ft), juniors aged 12 to 14 to 21 m (70 ft). The theory covers deep-dive planning, narcosis, compass work, nitrox and specialty dives.
Your deep training dive is on Saturday. Your instructor asks how much faster you’ll breathe down your tank at 30 m (99 ft), and what you’ll do if your computer shows a stop. Advanced Open Water is mostly a series of new dives, each with a short study session before it. This page covers your new limits, the theory for each dive and how to prepare.
What does Advanced Open Water let you do?
Once certified, you can plan dives to 30 m (100 ft), within your experience and the conditions of the day. The limit of all recreational diving is 40 m (130 ft), and going past 30 m (100 ft) calls for further deep diving training. A dive center or guide can always set a shallower limit for a given dive.
Despite the name, five supervised dives only introduce new skills. Build depth and experience step by step, in conditions close to those you trained in.
The figures below come from the public pages of the PADI Advanced Open Water course, read on November 11, 2026. Octo is an unofficial app, not affiliated with or endorsed by PADI. Other agencies, such as SSI, NAUI or CMAS, have similar but not identical advanced courses, with their own ages, depth limits and dive lists.
How deep can an Advanced Open Water Diver go?
30 m (100 ft) for adults. The published restrictions set these limits:
| Diver | Certification | Maximum depth |
|---|---|---|
| Aged 12 to 14 | Junior Advanced Open Water Diver | 21 m (70 ft) |
| 15 and over | Advanced Open Water Diver | 30 m (100 ft) |
| With further deep training | Deep diving specialty | Up to the 40 m (130 ft) recreational limit |
The course page counts any dive below 18 m (60 ft) as a deep dive, so the deep training dive takes you past your Open Water limit for the first time. Junior Advanced Open Water Divers become Advanced Open Water Divers automatically at 15.
Try a question from the app
depth limit
A week after your Advanced course, a friend invites you to dive a famous wreck at 40 m (130 ft).
Show the answer
Answer B. Advanced certification takes you to 30 m (100 ft); going deeper calls for further deep training. Nitrox wouldn’t help: common blends have an MOD shallower than 40 m (130 ft). A buddy or a computer doesn’t change your training.
What do you need to start Advanced Open Water?
An Open Water Diver certification, or its junior version, and an age of at least 12. The Advanced Open Water course page also accepts a qualifying entry-level certification, and it lists no minimum number of logged dives. Divers aged 10 and 11 can’t take the full course, but they can earn a Junior Adventure Diver certification, then complete the deep dive at 12 to become Junior Advanced Open Water Divers.
As for every course, you fill in a medical questionnaire, and some answers mean a doctor must clear you to dive.
Which dives are in the Advanced Open Water course?
Five in all. Two are required, deep and underwater navigation; you choose the other three with your instructor. The options depend on where you train: night, wreck, drift, boat, enriched air nitrox, buoyancy, dry suit, search and recovery, fish identification or underwater photography, among others. Each dive can count toward the matching specialty certification if you continue later.
The course page estimates 6 to 8 hours of eLearning and 2 to 3 days for the whole course.
What theory does Advanced Open Water cover?
The theory behind each dive: gas planning at depth, narcosis, what to do if you overstay your no-decompression limit, compass and natural navigation, nitrox limits and the techniques of each specialty. Octo covers it in 14 lessons.
| Module | Lessons in Octo | What you learn | Go deeper |
|---|---|---|---|
| Going further | 1 | What the course changes, your new limits | Open Water Diver |
| Deep diving | 3 | Planning a deep dive, narcosis and other deep-water risks, overstaying your no-decompression limit | Narcosis, dive computers and NDL, air consumption |
| Underwater navigation | 2 | Using a compass, natural navigation and patterns | Underwater navigation |
| Specialty dives | 8 | Buoyancy and trim, night, wreck, drift and boat, nitrox, search and recovery, dry suit, aquatic life | Nitrox and oxygen toxicity, buoyancy |
The key ideas, dive by dive:
- Gas at depth: at 30 m (99 ft), the absolute pressure is 4 bar (4 ata), so each breath takes four times the surface amount. Agree on a turn pressure and surface with at least 50 bar (500 psi).
- Narcosis: most divers notice it from about 30 m (100 ft). Ascending a little makes it fade; do it together.
- A required stop: if your computer shows a decompression stop, you must make it. Ascend slowly to the depth shown and stay until it clears.
- Compass: hold it level, with the lubber line along your body. To come back the same way, add or subtract 180° from your heading.
- Nitrox: keep the oxygen partial pressure at or below 1.4 bar (1.4 ata), with 1.6 for contingencies only, unless your agency or dive center sets lower limits. Analyze your own cylinder and set your computer before every dive.
Worked example
Maximum operating depth of EAN32. Divide the oxygen limit by the oxygen fraction, then turn that absolute pressure into a depth.
- Metric: 1.4 ÷ 0.32 = 4.375 bar; 4.375 − 1 = 3.375; × 10 = 33.75 m, rounded down to 33 m.
- Imperial: 1.4 ÷ 0.32 = 4.375 ata; 4.375 − 1 = 3.375; × 33 = 111.4 ft, rounded down to 111 ft.
Always round down: rounding up would take you past 1.4. The same steps give 28 m (95 ft) for EAN36.
Try a question from the app
gas use at depth
You breathe at the same pace at 10 m and at 30 m. How much faster does your gas run out at the deeper depth?
Show the answer
Answer B. What counts is absolute pressure: 2 bar at 10 m, 4 bar at 30 m, so twice as much gas per breath. Four times is the comparison with the surface; three times divides the depths instead of the pressures.
How is the Advanced Open Water knowledge part assessed?
Section by section, alongside the dives. The course page says the learning is done through eLearning sections matched to the dives you choose, and that your instructor schedules knowledge review sessions along with the dives. In a 2017 article for dive professionals, PADI explains that students answer short knowledge-check questions after each subtopic and complete a Knowledge Review for each section they study. The deep and navigation sections are strongly encouraged.
The rest happens in the water, on the five training dives. Formats change over time and between agencies, so ask your instructor how your course checks the theory.
Octo doesn’t include those Knowledge Reviews. Its questions are its own, written around the same topics.
How should you prepare for Advanced Open Water?
Refresh the basics, then read ahead for each dive:
- Review your Open Water basics: buoyancy, air checks, the safety stop. The Open Water practice questions are a quick check.
- Do the gas math for deep dives: absolute pressure, air use, turn pressure. See air consumption and SAC rate.
- Practice compass headings on land: reciprocal headings, a square, a triangle.
- Read up on each elective before its dive, especially nitrox if you choose it.
- Test yourself with the Advanced Open Water practice questions, then a timed practice exam.
All the formulas fit on one page: dive theory formulas.
Frequently asked questions
Can you take Advanced Open Water right after Open Water?
Yes. PADI’s prerequisites are an Open Water Diver certification, or its junior version, and an age of at least 12; its course page lists no minimum number of logged dives. A few fun dives in between can still help, since every training dive builds on your Open Water skills, especially buoyancy and air checks.
Do you need Advanced Open Water to dive to 30 m (100 ft)?
With PADI, yes. Open Water Divers stay above about 18 m (60 ft), and the Advanced Open Water certification takes adults to 30 m (100 ft), or 21 m (70 ft) for juniors aged 12 to 14. Past 30 m (100 ft), you need further deep training, and 40 m (130 ft) remains the limit of recreational diving.
Is nitrox part of Advanced Open Water?
It can be one of your three elective dives, depending on where you train. Octo’s nitrox lesson covers the basics: oxygen limits, maximum operating depth, analyzing your cylinder and setting your computer. The dive can count toward the full enriched air nitrox specialty, which you complete separately if you want to dive nitrox regularly.
Is Advanced Open Water hard?
PADI’s course page says it’s generally not considered difficult, especially compared with Open Water: it builds on skills you already have. Most of the work happens in the water, on the five dives. Arrive with steady buoyancy and good air habits, and read the theory for each dive before you go.
Does Advanced Open Water make you an expert diver?
No. After five supervised dives, you have tried new skills; you haven’t mastered them. Build experience gradually, go deeper step by step, and take the full specialty course for any kind of diving you want to make a habit. The official course page suggests the Rescue Diver course as a next step.
Sources
- Advanced Open Water Diver, official course page, requirements and FAQ (read November 11, 2026)
- Andrew Keaveny, diving restrictions by certification level, official blog (February 27, 2024)
- Scuba certification FAQ, official help center (read November 11, 2026)
- Advanced Open Water Diver eLearning, official blog for dive professionals (August 4, 2017)
