Marine Life Safety in Guam

Several marine species in Guam's waters carry venom that can cause severe pain, tissue damage, or in rare cases, be life-threatening. Learn to identify and avoid them.

• Stonefish: the world's most venomous fish, perfectly camouflaged on rocks and sandy seafloor. Their venom causes excruciating pain and can be fatal. NEVER walk barefoot on a reef.
• If stung by a stonefish: immerse affected area in hot water (as hot as tolerable) immediately to neutralize venom, and go to Guam Memorial Hospital emergency room without delay.
• Crown-of-thorns starfish: up to 18 inches across, covered in long venomous spines. If pricked: remove spines, soak in hot water, and seek medical attention.
• Lionfish: beautiful but venomous dorsal spines. Never touch even if it appears dead — reflex action can still inject venom.
• Cone snails: pick up NO cone-shaped shells ever. They fire a venomous harpoon that can penetrate wetsuits and cause paralysis.
• Sea urchins: painful spines that break off in the skin. Always wear reef shoes on reef flats.

• Moon jellyfish are the most common — their sting is mild, causing brief irritation in most people.
• Box jellyfish (more dangerous) are rare in Guam but can appear, especially after storms.
• Jellyfish sting first aid: remove tentacles using a credit card or stick (not bare hands); rinse with seawater (not fresh water); apply vinegar if available.
• For severe box jellyfish stings (intense pain, difficulty breathing, shock): call 911 immediately.
• Avoid swimming in jellyfish-heavy areas — if you see many jellyfish, exit the water and wait.

• Sharks are present in Guam's waters. Attacks on humans are extremely rare but do occur.
• Common species: whitetip and blacktip reef sharks — generally shy and not aggressive toward humans.
• Reduce risk: avoid swimming at dawn and dusk when sharks are most active.
• Remove shiny jewelry before entering the water — light reflection can resemble prey.
• Never enter the ocean with open wounds — blood in water can attract sharks.
• If you encounter a shark: stay calm, maintain eye contact, move slowly and back away toward the shore.

• Never stand on coral — it kills the reef, and coral cuts are painful and slow to heal.
• Do not touch, collect, or disturb any marine life — it is illegal in Guam's protected waters.
• Never attempt to "ride" sea turtles, mantas, or other large marine animals — it is illegal and harmful.
• Apply sunscreen before entering the water — on the beach, not in the ocean — to minimize chemical reef runoff.
• Fish feeding is prohibited in many of Guam's marine preserves and reef areas.
• Keep hands to yourself: don't put your hands in holes or crevices in the reef — moray eels live there.