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Coral cuts: small wounds that turn into big problems

A coral cut is trivial at the moment it happens and disproportionately troublesome afterwards. Coral carries bacteria and leaves fragments of calcium carbonate and living tissue in the wound, so a scrape that would heal in three days at home can become an infected, slow-healing ulcer in the tropics.

  • 5High risk
  • 14Medium
  • 1Low
  • 20Zones tracked

Fire coral is different

Fire coral is not a true coral but a stinging hydrozoan. Brushing it produces immediate burning pain and a raised red welt that can itch for weeks. It looks like ordinary mustard-yellow or brown coral with pale tips, which is why snorkellers grab it for balance.

Why infection is the real risk

Warm seawater bacteria, including Vibrio species, colonise coral wounds readily. The signs to watch for are increasing pain after 24 hours, spreading redness, heat and discharge. Left alone, these need antibiotics rather than plasters — and a holiday cut that is still worsening on day three is a reason to see a doctor, not to wait.

How to avoid it

  • Wear reef shoes, a rash vest and a wetsuit skin when snorkelling over shallow reef.
  • Never stand on, grab or steady yourself against coral — it damages the reef and cuts you.
  • Watch your fins; most coral contact is accidental fin or knee contact in shallow water.
  • Take particular care entering and exiting the water over a reef shelf in swell.

If it happens

  • Rinse thoroughly with clean fresh water and scrub gently to remove all fragments — this is the step people skip and the one that matters.
  • Flush with dilute antiseptic and keep the wound clean and covered.
  • For fire coral stings, rinse with seawater, remove particles, then use hot water or a topical antihistamine for the itch.
  • See a doctor if the wound is deep, if fragments remain, or if it is more painful and more red the next day.

General guidance only — not a substitute for medical advice or local emergency services.

Where we track it

20 zones in the Dangers Here hazard database, by danger level.

High

  • Cloudbreak / Mamanuca Reefs (Fiji)
  • Great Barrier Reef (Cairns–Port Douglas)
  • Hurghada / Giftun Islands (Red Sea)
  • Ras Mohammed / Sharm El-Sheikh (Red Sea)
  • Uluwatu–Padang Padang Reef (Bali)

Medium

  • Bermuda Reef Platform
  • Bonaire (Dutch Caribbean)
  • Cozumel (Mexico)
  • Florida Keys (Key Largo–Molasses Reef)
  • Gili Islands (Indonesia)
  • Gulf of Aqaba (Eilat & Aqaba)
  • Hanauma Bay (Oahu, Hawaii)
  • Maldives Atoll Reefs (North Malé)
  • Ningaloo Reef (Western Australia)
  • Okinawa & Ryukyu Reefs (Japan)
  • Phi Phi Islands (Thailand)
  • Roatán (Honduras)
  • Trunk Bay, St. John (US Virgin Islands)
  • Zanzibar — Mnemba & East-Coast Reefs

Low

  • Molokini Crater (Maui, Hawaii)

Questions

Where is sharp coral a risk?

We track 20 zones for this hazard. 5 are rated high risk, including Cloudbreak / Mamanuca Reefs (Fiji), Great Barrier Reef (Cairns–Port Douglas), Hurghada / Giftun Islands (Red Sea), Ras Mohammed / Sharm El-Sheikh (Red Sea), Uluwatu–Padang Padang Reef (Bali). 14 are rated medium and 1 low.

How do you avoid sharp coral?

Wear reef shoes, a rash vest and a wetsuit skin when snorkelling over shallow reef. Never stand on, grab or steady yourself against coral — it damages the reef and cuts you. Watch your fins; most coral contact is accidental fin or knee contact in shallow water.

What is the first aid for sharp coral?

Rinse thoroughly with clean fresh water and scrub gently to remove all fragments — this is the step people skip and the one that matters. Flush with dilute antiseptic and keep the wound clean and covered. For fire coral stings, rinse with seawater, remove particles, then use hot water or a topical antihistamine for the itch.

Fire coral is different

Fire coral is not a true coral but a stinging hydrozoan. Brushing it produces immediate burning pain and a raised red welt that can itch for weeks. It looks like ordinary mustard-yellow or brown coral with pale tips, which is why snorkellers grab it for balance.

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