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Great Hammerhead — illustration
AI-generated illustration for The Scuba Atlas — illustrative, not a documentary photograph.

Sharks

Great Hammerhead

Sphyrna mokarran · Cartilaginous fish — family Sphyrnidae

IUCN: CR (decreasing) ~3.5 m total length; most animals on dive sites run 3–4.5 m 1–80 m depth band Well documented

Seeing a great hammerhead approach across white sand is one of diving's great set pieces: a dorsal fin like a yacht sail, then the improbable meter-wide head swinging in slow arcs. This is the largest hammerhead, a specialist ray hunter that pins prey to the bottom with its cephalofoil before biting. It travels alone, which makes the reliable winter encounters in the Bahamas so unusual and so valuable. For all its presence in person, the species is in serious trouble — its fins command high prices, and it dies quickly on fishing gear even when released.

Respect factor: Treat With RespectA very large, capable predator with rare recorded incidents. On organized feeds it is purposeful rather than aggressive; maintain position, keep your hands in, and follow the feeder's briefing.

Where and when to see one

"Resident" means most dives at that destination encounter them; "seasonal" means reliably present in the listed months; anything else is a bonus, not a plan.

DestinationReliabilityMonthsNotes
Tiger Beach & Grand BahamaThe Bahamas Seasonal — reliable in season Dec–Mar
RangiroaFrench Polynesia Seasonal — reliable in season Dec–Mar
Brothers, Daedalus & St John'sEgypt Occasional May–Aug
Florida KeysUnited States Occasional Dec–Apr
Jardines de la ReinaCuba Occasional Year-round

Best month, at a glance

Understanding them

Habitat: Coastal shelves, reef edges, and sand flats; ranges into very shallow water when hunting rays

Range: Circumtropical in warm coastal seas — the wider Caribbean, Red Sea and Indian Ocean, northern Australia, and the central Pacific

Behavior: A solitary, wide-roaming hunter, unlike its schooling scalloped cousin. The exaggerated cephalofoil is packed with electroreceptors and works like a metal detector swept over sand; the tall sickle of a first dorsal fin often shows before the animal itself. Around baited dives it moves with deliberate, unhurried confidence.

Diet: Rays and skates above all — stingray barbs are routinely found in their jaws — plus other sharks, groupers, and cephalopods

Size: typically around 3.5 m; documented up to 6.1 m (total length; most animals on dive sites run 3–4.5 m).

How to behave around one

Stay low and settled on sand-bottom feed dives, avoid blocking its swim path, no touching as it passes, and never freelance with bait. In open water, hold your depth and let it choose the distance.

Conservation

Critically Endangered — overfishing for the fin trade and severe bycatch mortality have cut global numbers steeply. Encounter tourism in the Bahamas, where sharks are protected, is a genuine conservation asset.

Charted sites known for them

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Sources: Wikipedia ↗IUCN Red List ↗ · Facts verified against the sources above; fields without support are labeled not yet verified.

Australia, New Zealand & East Asia

Cairns & the Ribbon ReefsNingaloo ReefCoral Sea & Osprey ReefOkinawa & the Kerama IslandsPoor Knights IslandsTownsville & the YongalaGreen IslandIzu Peninsula

Caribbean & Western Atlantic

BonaireCozumelRiviera Maya & the CenotesBelize Barrier ReefGrand CaymanIsla Mujeres & CancúnRoatánTiger Beach & Grand Bahama

Europe, Atlantic & Mediterranean

Malta & GozoSilfra & IcelandThe AzoresCanary IslandsLarnaca & the ZenobiaScapa FlowArctic NorwayMadeira

Indian Ocean & East Africa

North & South Malé AtollsAri AtollBaa Atoll & Hanifaru BayAliwal Shoal & UmkomaasMafia IslandMauritiusSeychellesSodwana Bay

Pacific Islands & Micronesia

PalauChuuk (Truk) LagoonFakaravaKona, HawaiʻiRangiroaTaveuni & Rainbow ReefBeqa Lagoon & Pacific HarbourEspiritu Santo

Red Sea & Middle East

Sharm El Sheikh & Ras MohammedBrothers, Daedalus & St John'sDahabHurghada & El GounaMarsa Alam & the Deep SouthAqabaDaymaniyat IslandsMusandam Peninsula

Southeast Asia & Coral Triangle

Bali & Nusa PenidaKomodoRaja AmpatSipadan & MabulAnilaoCoronKoh TaoLembeh Strait

The Americas & Eastern Pacific

Galápagos IslandsCocos IslandFlorida KeysSea of Cortez & Cabo PulmoSocorro & the RevillagigedosBritish ColumbiaCalifornia Channel IslandsCosta Rica Pacific Coast