Dive Magazine has launched a short online quiz, "Your Body Underwater", that tests how well you understand what happens to the human body beneath the surface — the physics of pressure, how breathing works underwater, and the basic science that keeps scuba divers safe. It takes about a minute to complete, which makes it a fun warm-up before a dive course or a quick refresher if your last dive was a few years ago.
The topic is more relevant to holidaymakers than it might sound. Every year, thousands of travellers book discover-scuba sessions or full Open Water courses in places like the Red Sea, Thailand's Koh Tao, and the Great Barrier Reef, often with little idea of what they're signing up for physically. The core concepts the quiz touches on are the same ones an instructor will drill in your first day: how water pressure increases as you descend, why you must never hold your breath, and how air spaces in your ears and sinuses need to be equalised on the way down.
A few of the basics worth knowing before any resort dive. At around 10 metres, the pressure on your body roughly doubles compared to the surface, which compresses the air in your wetsuit, your mask and your lungs. That's why breathing from a regulator feels no different from breathing on land — the air is delivered at ambient pressure — and why ascending while holding your breath is the single most dangerous mistake a diver can make: expanding air has to go somewhere. Equalising your ears early and often prevents the painful squeeze that ruins first dives.
Depth also affects your air supply and your head. Compressed air gets used faster the deeper you go, and nitrogen absorbed under pressure can produce a mild narcotic fuzziness below about 30 metres — nothing recreational divers at beginner depths need to worry about, but a good reason to respect training limits. Dehydration, alcohol the night before and poor fitness all make these effects worse, so the ideal dive holiday involves water, sleep and not too much sun before your first descent.
Who is this for? Anyone considering their first dive on a beach holiday, snorkellers curious about graduating to scuba, or lapsed divers wanting a refresher before booking a liveaboard trip. The quiz itself is light entertainment rather than training — nothing replaces a proper certification course — but it's a useful gut-check on whether you understand the environment you'd be entering. If you score badly, that's not a reason to skip diving; it's a reason to book the full course with an instructor rather than a quick try-dive.
Dive Magazine publishes regular quizzes and features on diving science and destinations, and this one slots neatly into that series. Take it before your next trip, then find a reputable dive centre affiliated with a major agency — PADI, SSI or BSAC — and ask questions. The ocean is far more enjoyable when you know what your body is doing down there.
