Can You Actually Learn to Dive? The Medical Checklist No One Explains

You watched a dive video, you're ready to book the course, and then somebody hands you a three-page medical form with 20 yes-or-no questions. Suddenly you're wondering if that childhood asthma inhaler is about to wreck your dream trip. Take a breath — most people who fill in this form are cleared to dive. But the form exists for real reasons, and knowing what it's actually asking before you show up saves you time, money, and a wasted flight.

This is the honest breakdown of the scuba medical questionnaire, written for the total beginner. We'll cover what doctors worry about, what gets you an automatic no, and what gets you a "sure, just see your GP first."

Why a medical form exists at all

Diving looks gentle, and at 18 metres on a calm reef it pretty much is. But your body is under roughly three times surface pressure, breathing compressed gas, in an environment where you can't just stand up and walk out. Certain conditions — a collapsed lung you didn't know about, an irregular heartbeat, a seizure — are survivable at sea level and potentially fatal underwater. The form is a filter, not an insult.

Since 2020 almost every major agency (PADI, SSI, SDI, NAUI) uses the same RSTC Diver Medical Participant Questionnaire. It's ten questions on page one. Answer NO to all ten and you're ready to dive. Answer YES to anything and you'll need a doctor's signature before you can get in the water.

The hard disqualifiers — the real short list

Very few conditions are absolute no-gos, but these are the ones diving physicians consistently refuse to clear:

• Uncontrolled epilepsy or recent seizures — losing consciousness underwater is almost always fatal.
• Active pneumothorax or history of spontaneous lung collapse — air expanding on ascent can rupture lung tissue.
• Severe COPD or emphysema — same gas-trapping concern.
• Uncontrolled heart failure, recent heart attack, severe coronary artery disease — diving is moderate exercise in cold water, a classic trigger.
• Pregnancy — the effect of dissolved nitrogen on a fetus is unknown, so every agency says no until after delivery.
• Active ear infection or ruptured eardrum — you physically cannot equalise.

Notice how short that list is. Most things you're worried about aren't on it.

The "it depends" list — doctor's note required

This is where most nervous beginners actually fall, and the good news is the vast majority get cleared:

• Asthma — mild, well-controlled, no exercise-induced or cold-induced attacks in recent years? Usually cleared after a lung function test. Needing a rescue inhaler weekly? Probably not.
• Diabetes — type 2 on oral meds, stable, no hypoglycaemia episodes? Usually fine with a dive-savvy GP's approval. Poorly controlled type 1 is harder.
• High blood pressure — controlled on medication is almost always cleared.
• ADHD / antidepressant medication — stable dose, no sedation issues, generally fine.
• Previous ear surgery, grommets, perforated eardrum history — needs an ENT check to confirm you can equalise safely.
• Back or spine problems — can you carry a 15kg tank? That's the real test.
• Anxiety or claustrophobia — not disqualifying, but worth an honest conversation with your instructor; Discover Scuba first is smart.

Age — younger and older than you think

The minimum age for a Junior Open Water certification is 10. Under-15s are limited in depth (12m, then 18m after 12 years old) and must dive with a certified adult. Bubblemaker and Seal Team programs go down to 8 in pool-only settings.

There is no upper age limit. Plenty of divers are still active in their 70s and 80s. What matters after 45 is cardiovascular fitness — if you get winded climbing two flights of stairs, see your doctor before you book the course. A basic cardiac check is cheap insurance.

The swim test — the real fitness bar

This is the one people underestimate. To get certified at entry level you must, in a pool or calm water:

• Swim 200 metres continuously — any stroke, no time limit, no stopping. (Or 300m with mask, fins and snorkel.)
• Float or tread water for 10 minutes — any method, no flotation aid.

That's it. You don't need to be fast, you don't need technique, you just can't panic in the deep end. If you can comfortably swim a few lengths of a hotel pool you're already there. If you can't, spend three weeks at your local pool before the course — it's honestly the best preparation you can do.

Ears and sinuses — the number one reason beginners struggle

Forget asthma and heart — the most common reason new divers get stuck on day one is they can't equalise their ears. A lingering cold, chronic sinusitis, or a deviated septum can turn your first descent into a painful stop at 3 metres. Rules of thumb:

• Never dive with a blocked nose, even a mild one. Decongestants help but wear off mid-dive — that's worse than not diving.
• If you have chronic sinus issues, see an ENT before the trip, not after.
• Learn the Valsalva, Frenzel, and Toynbee techniques before day one. YouTube has excellent tutorials.
• Equalise early, equalise often — before you feel pressure, not after.

If you answered YES on the form — what actually happens

Don't panic and don't lie. Thousands of divers with asthma, diabetes, heart stents, and more are cleared every year. The process is:

1. Take the full three-page form (pages 2 and 3 are for the doctor) to your GP or a dive medicine specialist.
2. They do a basic exam — blood pressure, heart, lungs — and may order a lung function test if asthma is on the form.
3. They sign, date, and stamp the clearance section. Valid for 12 months in most regions.
4. You hand it to your dive shop on day one. Done.

Cost in most countries is the price of a standard GP visit. In Thailand, dedicated dive medicine doctors in Phuket and Koh Samui charge around 1,500–2,500 THB and will see you same-day.

Still unsure? Start with a Discover Scuba

If you're genuinely on the fence — maybe it's a health question, maybe it's anxiety in the water — don't commit to a four-day course. Book a Discover Scuba Diving (DSD) experience instead. One pool session and one shallow open-water dive, under direct instructor supervision, no certification. You'll know within an hour whether diving is for you and whether your ears, lungs, and nerves cooperate.

At SiamDive we run DSDs and full Open Water certifications across Phuket, Phi Phi, and Similan daily, with instructors who've seen every version of the medical form. If you have a question about a condition, message us before you book — we'd rather tell you honestly than see you turned away at the boat.

This article is general information, not medical advice. Any dive medical clearance must come from a qualified physician familiar with diving medicine.