What to do if an earthquake happen during scuba diving

If you are already underwater when the earthquake starts, a more detailed procedure would be:

1. Stop and assess

   • Do not immediately ascend.

   • Signal your buddy and stay together.

   • Check that you are neutrally buoyant.

2. Look for hazards

   • If you are close to a reef wall, steep slope, cave, wreck, or overhang, move slowly into open water.

   • Watch for falling rocks, coral fragments, or clouds of sediment.

3. Protect yourself from debris

   • If debris is falling, hold your regulator securely in your mouth.

   • Protect your mask with one hand if necessary.

   • Maintain buoyancy to avoid being pushed into the bottom.

4. Monitor conditions

   • Check your depth, no-decompression status, and air supply.

   • Visibility may drop suddenly due to disturbed sand and silt.

   • Strong local currents may develop near underwater terrain.

5. Stay below the surface initially

   • Do not rush to the surface unless there is an immediate life-threatening hazard.

   • A rapid ascent creates a greater risk of lung overexpansion injury or decompression sickness than the earthquake itself.

6. End the dive conservatively

   • Once the shaking stops and conditions permit, begin a controlled ascent with your buddy.

   • Follow your normal ascent rate.

   • Complete a safety stop if conditions allow and your air supply is adequate.

7. After surfacing

   • Inflate your BCD and establish positive buoyancy.

   • Look for your boat and listen for instructions.

   • If the earthquake was strong or lasted a long time, assume there could be a tsunami risk.

   • Follow the boat crew's emergency procedures immediately.

Special situations

Cave diving

• Stay calm and maintain contact with the guideline.

• Expect silt-outs from disturbed sediment.

• Exit using standard lost-visibility procedures if necessary.

Wreck diving

• Watch for falling rust, plates, cables, and interior collapses.

• Consider terminating the dive immediately and exiting the wreck.

Deep diving

• Be especially careful not to violate decompression obligations.

• An uncontrolled ascent can be more dangerous than remaining underwater during the quake.

For dive leaders and instructors

A practical SSI-style briefing point is:

"If we feel shaking or hear unusual rumbling underwater, stay with your buddy, move away from overhead environments and unstable structures, maintain buoyancy, and end the dive with a normal controlled ascent. Do not make a rapid ascent solely because of the earthquake."