How do you get your first diving certification? What the Open Water course really involves, PADI vs. SSI vs. CMAS, and how the level ladder continues.
The question almost everyone asks before starting: Do I really need a course just to breathe underwater? The honest answer: yes, absolutely — and the course is shorter and simpler than you think. Scuba diving means: you carry a tank of compressed air and a regulator, letting you stay underwater for hours instead of seconds. That extra time brings new risks with it — pressure, gas laws, decompression — and you learn those in certification, not by accident on a beach.
The major diving organizations PADI, SSI and CMAS built a global system for this that has worked for decades: PADI alone has certified over 30 million divers since 1966 and issues around 80% of all certifications worldwide. In 2024, PADI added over 1.3 million new certifications — scuba diving is one of the most standardized recreational sports there is.
The entry-level course is usually called Open Water Diver (PADI and SSI) or CMAS \ — the names differ, the structure is nearly identical. You learn four pillars there: theory, exercises in a pool or calm water for good reason, real dives in the sea or a lake, and a final exam. Train Smart. Play Hard.* here means: nail the basics cleanly first, then enjoy the depth.
You learn pressure and gas laws, the basics of dive tables or dive computers, equipment and safety rules — usually online or self-study, taking 6–8 hours. That sounds like a lot, but it's split into bite-sized videos and quizzes, not a lecture hall.
Before heading out, you practice in a pool or calm water: clearing your mask, recovering your regulator, controlled ascents. Mistakes happen safely here, not at 15 meters. This is also where you first practice the emergency ascent without air — one of the most important skills you'll learn.
The PADI standard calls for four dives: the first two to a maximum of 12 meters, the last two to a maximum of 18 meters. After these four dives you're certified — not perfect, but safe enough for supervised and soon independent diving.
Open Water is the entry point, not the destination. Next usually comes Advanced Open Water (more depth, trying out specialties), then Rescue Diver (emergency management for others), and if you want, Divemaster as the first professional level. Each level builds step by step on the last — no agency expects you to finish all of it on one vacation.
PADI, SSI, CMAS, SDI, or national agencies differ in details, but certifications are recognized worldwide across each other. More important than the logo on the card is the quality of the local dive center and whether you click with the instructor.
Certification isn't a bureaucratic ritual, it's the reason scuba diving is so safe when done right. Fill out the medical self-declaration honestly — cardiovascular issues, asthma or middle-ear problems aren't automatic disqualifiers, but they need a doctor's clearance beforehand.
Choose a dive center with visible standards: maintained gear, small groups, clear emergency plans. And accept that a good instructor might pull you out of the water if something's off — that's care, not harassment.
Do the theory online before your trip if your agency offers it (PADI/SSI eLearning). Then you spend your vacation time in the water instead of a classroom — and arrive with your head already clear for the first skills.
A trick experienced divers pass on: ask the dive center about group size per instructor. Agencies set a maximum, but good centers voluntarily go below it — a reliable quality signal.
Usually 3–5 consecutive days, split into theory (6–8 hours), skills in calm water and four open-water dives. Many centers also offer the theory as eLearning beforehand, so you're in the water faster once you arrive.
All three are recognized worldwide and structurally very similar. PADI is the most widespread with around 80% market share, while SSI and CMAS have strong networks in Europe. The dive center's quality matters more than the agency.
Open Water certification usually allows dives to 18 meters — deeper than most reefs beginners want to see anyway. For greater depths you need the Advanced course, which usually raises the limit to 30 meters.
Junior certifications are often available from age 10 with depth and supervision restrictions, full certification usually from 15. There's no fixed upper limit — as long as your health allows it, you can start at 60 or 70 too.
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