PADI vs SSI vs NAUI — which should you choose?
Updated 2026-06-30 · Certification
PADI, SSI and NAUI are the three best-known scuba training agencies, and here's the honest answer: for an entry-level diver they're far more alike than different. All three are globally recognised, follow the same international training standards (ISO/WRSTC), teach the same core theory, and certify you to the same 18 m (60 ft) Open Water limit. A card from any of them is accepted at dive centres worldwide.
So the real decision isn't the logo — it's the dive centre, the instructor and the schedule near you. That said, there are a few small differences worth knowing.
What they have in common
The things most beginners worry about are identical across all three:
- ·Recognition: all are accepted worldwide and cross-honoured — you can start with one and continue with another.
- ·Depth limits: 18 m / 60 ft entry level, 40 m / 130 ft recreational maximum.
- ·Course structure: theory + exam, confined-water skills, then open-water dives.
- ·Core theory: the same physics, physiology, planning and safety — and the same kind of written exam.
The small differences
PADI is the largest and most marketed, so you'll find PADI centres almost everywhere and resale of materials is easy. SSI ties certification to an affiliated dive centre and offers its theory and digital materials free through the shop, which can make it cheaper. NAUI has a reputation for giving instructors more latitude in how they teach, and is popular with clubs, universities and the military. None of these makes you a 'better' diver — that comes from the instructor and your practice.
How to actually choose
Pick the dive centre and instructor you trust, with a schedule and class size that suit you, at a fair price — then go with whatever agency they teach. A great instructor on any agency beats a mediocre one on your 'preferred' brand. The theory you'll study is essentially the same, which is why one prep system works regardless of the badge on your card.
Frequently asked questions
Is PADI better than SSI or NAUI?+
Not in any way that matters to a new diver. All three are internationally recognised, follow the same standards, and have the same depth limits and core theory. PADI is simply the largest and most widely available; SSI and NAUI are equally valid certifications.
Are PADI, SSI and NAUI certifications interchangeable?+
Yes. They're cross-honoured worldwide — you can certify Open Water with one agency and take your Advanced course with another, and any dive centre will accept your card to rent gear or join dives.
Will one study system prepare me for any of them?+
Yes. Because all three test the same core theory — physics, equipment, dive planning and safety — a single well-built prep system covers the written exam regardless of which agency you choose.