The quality of your dive training depends 80% on the specific instructor and 20% on the agency (PADI, SSI, CMAS). Yet beginners pick dive centres by the logo on the door or the advertised price. This guide covers the real criteria for assessing an instructor before committing to a course — no marketing, no fluff.
Question 1: how many students will your instructor have on your course? Ideal ratio: 1:1 to 1:4. Acceptable: 1:6. Poor: 1:8 or more. With eight students, individual attention disappears and struggling beginners go unnoticed until problems escalate. If the centre tells you 'there could be up to eight', find another centre or pay for a private course.
Question 2: how many years has this specific instructor been teaching? The gap between one year and ten years of instruction is vast. An instructor with 1,000 courses behind them spots common issues — pool stress, underwater disorientation, equalisation problems — within seconds. A recent instructor may take minutes to register the same signal. For anxious beginners, that difference is not small.
Question 3: does the instructor speak your language fluently? Dive instruction involves precise technical vocabulary: partial pressure, decompression, narcosis. An instructor who manages tourist-level conversation but lacks technical fluency leaves you missing roughly 30% of the content. For courses at a tourist destination — Egypt, Thailand — confirm genuine language proficiency, not just basic comprehension.
Question 4: does the instructor have experience with students like you? An instructor who mostly teaches young adults in tropical water is not the obvious choice for an older student with water anxiety. An instructor specialised in children is not the obvious choice for someone seeking a technical pathway. Ask directly: 'what percentage of your courses last year involved beginners over 50?' — or whatever matches your own profile.
Question 5: what is the completion rate? Ask how many students finish the course versus how many drop out or fail. An honest instructor will tell you. A rate of 95–98% is typical; below 90% may signal poor student screening, an overly rigid teaching style, or consistently difficult conditions. Above 99% consistently can mean students who are not ready are being passed — which carries its own risks down the line.
Warning signs: 1) the centre promises a 'guaranteed course' with no possibility of failing. 2) The price is significantly below local competition — 50% less is usually a sign of cuts somewhere. 3) The instructor has negative reviews on TripAdvisor or Google citing safety or supervision issues. 4) The centre is evasive about what the OWD course actually covers. 5) There is no personal kit — everything is always rented out — suggesting very high student turnover.
Things few people consider: 1) reviews on diving-specific platforms — Scubaboard, ScubaEarth — and local forums. 2) Word-of-mouth recommendations from experienced divers in your area. 3) Additional languages: if you are diving in an international group, a multilingual instructor is a genuine asset. 4) Site-specific knowledge: a local instructor with ten years on the same dive site understands the currents, the visibility patterns, and the entry points in ways that cannot be replicated by a generic centre.
The certificate is the same wherever you train; the knowledge is not. Spending 50–150 € more — the typical gap between a cheap instructor and a good one — buys training that shapes your entire diving career. For foundational courses (OWD, Advanced), prioritise an experienced instructor over price. For advanced courses (Rescue, technical, cave), a specialised instructor matters more than which agency issues the card. If your first instructor taught you well, going back to them for the next course makes sense.