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Scalloped Hammerhead Schools
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shark aggregation

Scalloped Hammerhead Schools

Scalloped hammerhead · Sphyrna lewini

advancedmedium confidenceBucket-list rank #3
TL;DR — Best in Cocos Island, Costa Rica · Jun · Jul · Aug · Sep · Oct · Nov · ~$5500–$9500/day.

Daytime schooling aggregations of scalloped hammerheads at seamounts and current-swept island walls.

When

JanFebMarAprMayJunJulAugSepOctNovDec

Where

  • Cocos Island

    Costa Rica

    Best current option

    Jun · Jul · Aug · Sep · Oct · Nov

    Liveaboard-only seamount with reliable hammerhead aggregations at cleaning stations.

    Open Cocos Island in atlas →

  • Wolf Island

    Ecuador

    Best current option

    Jun · Jul · Aug · Sep · Oct · Nov

    Northern Galápagos current convergence; one of the densest schooling sites in the world.

    Open Wolf Island in atlas →

  • Darwin Island

    Ecuador

    Best current option

    Jun · Jul · Aug · Sep · Oct · Nov

    Sister site to Wolf with comparable aggregation density.

    Open Darwin Island in atlas →

  • Malpelo

    Colombia

    Best current option

    Jun · Jul · Aug · Sep · Oct · Nov

    UNESCO-protected seamount with hammerhead and silky shark aggregations.

    Open Malpelo Island in atlas →

  • Socorro

    Mexico

    Still happens

    Nov · Dec · Jan · Feb · Mar · Apr

    Hammerheads appear seasonally alongside the more famous giant manta encounters.

    Open Socorro Islands in atlas →

Ethics

Stay grouped, breathe shallowly, no flash photography at the school. Operator briefings supersede general guidance.

Operators

We don’t accept payment for listings. Operators are included when they appear in regulator permit lists or have an established track record at the site — we mark each one as verified only when we’ve cross-checked the permit ourselves.

  • Cocos Island, Costa Rica

    • Undersea Hunter Group

      listed only

      $5500–$8500 · 10 days · max 18

      Pioneering Cocos liveaboard operator since the 1990s.

      Visit operator site →

  • Wolf Island, Ecuador

    • Galapagos Master

      listed only

      $6500–$9500 · 7 days · max 16

      Master Liveaboards-operated Wolf/Darwin itinerary; northern Galápagos focus.

      Visit operator site →

Required experience

Advanced Open Water minimum, comfort with strong current, blue-water hangs, and deep multilevel profiles. Reef-hook training recommended.

Conservation

Scalloped hammerheads are Critically Endangered (IUCN). Aggregations are sensitive to repeated disturbance.

Limitations

Schooling behavior varies with current, lunar phase, and water temperature. Encounter frequency is reported by liveaboard operators rather than measured against a survey denominator.

Sources & methodology

How we summarise this

Schooling behavior is operator-reported. Aggregation density varies with current, lunar phase, and temperature.