Scuba diving when travelling

At 10 metres, the pressure is already double the pressure at the surface. The air in your ears, sinuses and lungs is compressed as you go down and expands as you come up.

Under pressure, nitrogen from the air you breathe dissolves in the body; when you come up slowly, it leaves through the lungs. When you come up too fast, it forms bubbles, like a bottle of fizzy drink opened all at once: this is decompression sickness.

Deeper than 30 metres, nitrogen also affects the brain, a bit like alcohol: this is the "rapture of the deep".

Diving centres often ask for a medical certificate. You need a medical opinion if you have:

• asthma, another lung disease, or a past collapsed lung (pneumothorax);
• a heart condition or diabetes;
• epilepsy, fainting spells or loss of consciousness;
• an ear or sinus problem, or past ear surgery;
• depression, anxiety or a fear of enclosed spaces;
• a regular medical treatment.

Do not dive during pregnancy. For a child, ask a doctor's advice.

Avoid sedatives, sleeping pills, strong painkillers, medicines that make you dizzy, and nasal sprays used for several days.

Malaria area? There is no malaria prevention advice specific to divers: follow the prevention prescribed for your destination. Try any new medicine a few days before you leave.

• Long break from diving? Take a refresher course, at a reputable centre.
• Check that your insurance covers diving accidents and repatriation.
• Find the nearest recompression chamber; on a remote island it can be hours away.

• Never dive alone, and do not dive if you are tired, ill or have a cold.
• Stay within the limits of your diving certification and respect the decompression stops on your dive computer.
• No more than 2 dives per day.
• Wear a wetsuit, even in warm water.
• On the way down, equalise your ears often, without ever forcing. On the way up, breathe normally: the air in your lungs expands and can tear them if you hold your breath.
• Ear or sinus pain? Stop diving and see a doctor locally.

The body keeps dissolved nitrogen for several hours. On a plane, the cabin pressure is the same as on a mountain 2000 to 2500 metres high: bubbles can form. Wait:

• at least 24 hours after your last dive;
• up to 48 hours after dives with mandatory decompression stops.

The same waiting times apply before going up to altitude, for example over a mountain pass. After arriving by plane, rest before your first dive.

In the 24 hours after a dive, watch out for:

• joint or muscle pain, even "minor" pain, itching or patches on the skin;
• tingling, weakness or paralysis in an arm or a leg;
• dizziness, problems with vision or speech, confusion;
• difficulty breathing, chest pain, extreme tiredness.

1. Lay the person down and give them pure oxygen as soon as possible.
2. Call the local emergency services. If the person is no longer breathing, start resuscitation.
3. Call DAN Europe on +39 06 4211 5685, 24 hours a day.
4. Treatment takes place in a recompression chamber, as quickly as possible.
5. Do not fly until a doctor says you can.

In Switzerland, emergencies: 144. Abroad: the local emergency number.

• "I followed my dive computer, so I can't have an accident." False. The rules reduce the risk, but do not remove it.

Symptoms appear after you get back? See a doctor and say that you have been diving. After an accident, do not dive again without the approval of a diving medicine doctor: we can refer you.