When and where to dive with hammerheads

Hammerhead season is not one season

Ask when hammerhead season is and most answers name one place’s calendar: June to November for Cocos and the Galápagos, winter for Bimini. Put the places side by side and there is no single season at all. The schools peak at different places in different months, and in every month of the year at least two of the sixteen places in the chart below that are still open to divers are at their peak. The leanest month is May, with two, and September comes next with three. The richest are January and February, with seven.

So the question is not when to go but where to go in the month you can travel. The rest of this guide answers that for each region: what the dive is, how deep it runs, what the current does, and in which months the sharks are there.

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  <img src="https://reefwander.com/og/diagrams/hammerhead-calendar.svg" alt="When the hammerheads are there, against how we rate the diving. Amber is the months the sharks are reported, solid where every source agrees; the strip beneath is the area’s season rating. The rows step through the year, and no month is empty." loading="lazy">
  <figcaption>Diagram by Reefwander, licensed under CC BY 4.0.</figcaption>
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Two things about how the chart was built. The amber bars are the months the sharks are reported at each place. Where the sources we read name different windows, the pale bar covers every month any of them names and the solid part only the months they all agree on, so the solid block is the safe booking window rather than the widest claim. The thin strip under each row is our own season rating for the area. That rating describes the diving (sea state, access, when the boats run), not the animals, and it was set separately from the shark months.

Mostly the two agree. At Cocos, the Galápagos, Tiran and Yonaguni every peak month is also rated prime, as it was at Layang-Layang while its resort ran, and the great hammerhead peaks at Bimini and Rangiroa fall in prime months too. They split in four places, and the split is worth knowing before you pay. Fuvahmulah’s schools are best from October to December, when the thermocline is shallower, but October and November are the choppy monsoon transition and we rate them fair. Protea Banks’ scalloped schools run through November and December, which are the two months we rate fair there. Sudan’s hammerheads are at their most reliable from February to April, and February is still a rough-weather month for the crossing. And Socorro’s season opens in November, a shoulder month for the liveaboards. In each case the sharks are there and the sea is not at its kindest; decide which you care about more.

Two sharks, two different dives

Most hammerhead diving is with one of two species, and they are different trips.

The scalloped hammerhead is the one that schools. The pattern was first worked out at El Bajo in the Sea of Cortez: by day the sharks gather in groups over a seamount or an island slope, mostly females, with the larger females holding the centre of the school and competing for that position with short displays. At night they leave and hunt alone, offshore and deep. How deep was shown in 2023, when sharks tagged off Hawaiʻi Island were recorded diving past 800 m at night, one to 1,044 m, from surface water around 26 °C into water near 5 °C. Video showed the gill slits held shut on the way down. The sharks were holding their breath to keep their body heat, the way a diving mammal does, and opening their gills again only once they were back in warm water.

That day and night split is the whole basis of hammerhead diving. The sharks come to a fixed piece of rock at a predictable hour, and they come closest at cleaning stations, where barberfish and wrasse pick parasites off their skin, and in the first hour of light. Nearly every scalloped site below is a seamount, a pinnacle or the outside corner of a reef in current, and nearly every dive is made early.

The great hammerhead is the largest of the family, averaging about 4.6 m and recorded past 6 m, with a straight front edge to its head and a tall, sickle-shaped first dorsal fin. It is a solitary hunter and eats stingrays among much else; stingray spines are often found lodged in its mouth. Divers meet it in shallow water over sand, usually on a baited dive, and in winter. Tagging in Florida and the Bahamas found great hammerheads resident off Bimini and Jupiter mainly from October to March, some of the same animals returning several winters in a row, and one shark covering a return migration of about 3,030 km.

A third species, the smooth hammerhead, is the one most at home in temperate water, but no dive in this guide is built around it.

Scalloped and great hammerheads are both assessed as Critically Endangered, and all hammerheads are listed on Appendix II of CITES, which regulates the fin trade: the scalloped, great and smooth species since 2013 and the rest of the family since 2022. The places that still hold schools are places that protect them, and a dive trip is one of the few ways that protection pays for itself.

Month by month

The chart reads across by place. This is the same information read down by month, for the trip you can take.

January to March. The richest stretch of the year. Great hammerheads are at their most reliable at Bimini and Tiger Beach in the Bahamas and at Rangiroa in French Polynesia, where the austral summer is great hammerhead season. In the scalloped world, Yonaguni in Japan is at its best, Socorro’s liveaboard season is in full swing, Protea Banks’ summer schools are still running, and Sudan’s hammerhead months are under way.

April and May. The schools move. Layang-Layang’s schools peak in April and May, though the atoll has been closed to divers since January 2025, Malapascua’s short peak closes after March and April, and in the Red Sea the first hammerheads arrive at Daedalus in April and are shallow through May and June. May is the leanest month on the chart.

June to August. The eastern Pacific takes over. Cocos and the Galápagos are at their peak from June to October in cool, plankton-rich water, which brings the biggest schools and the lowest visibility. Mikomoto’s recommended season starts in June, Daedalus and the Brothers are at their best, and Tiran’s hammerheads peak in July and August.

September and October. Cocos, the Galápagos and Mikomoto are still going. The Banda Sea’s seamount hammerheads arrive, Fuvahmulah’s schools come in from October, and South West Rocks and Protea Banks start their southern-summer seasons. September is the next leanest: the Red Sea is fading and most of the winter sites have not begun.

November and December. Fuvahmulah is at its peak, Protea Banks and South West Rocks are in full season, Socorro’s liveaboards start again, great hammerheads are back at Bimini, and at Tiger Beach from December, and Rangiroa’s season begins.

The eastern Pacific: Cocos, Galápagos, Malpelo, Socorro and La Paz

This is where the great schools are. At Darwin's Arch divers drop onto a rocky slope off Darwin Island and hold position between 18 and 24 m (60 to 80 ft) while scalloped hammerheads and Galápagos sharks stream past the blue edge; from early July, whale sharks join them. The current is strong and the technique is simple: stay low on the rock and do not swim against it. The rock arch that gave the site its name collapsed in 2021, and the diving is unchanged. At Wolf Island, Shark Bay starts shallower, on rock at 8 to 10 m, and works down to a sandy patch at about 25 m where divers hold onto outcrops and watch the blue for schools of a dozen or more.

Bajo Alcyone off Cocos Island is the purest version of a hammerhead dive: a seamount whose summit sits at 25 m, reached by a fast negative descent, after which you wedge into the rock and wait while the school fills your field of view. Dirty Rock and the arch at Dos Amigos Grande are the other classic Cocos sites. At Manuelita the cleaning stations sit on boulders at 30 to 35 m on the islet’s west side, where hammerheads, some around 4 m long, queue for the barberfish. Punta Maria is a seamount with nothing shallower than 18 m, so nitrox is recommended. Hammerheads are at Cocos all year, but the densest schools come in the rainy season from June; in the dry months from December to May the water is calmer and clearer and the sharks fewer.

The two islands are linked. Acoustic tags on scalloped hammerheads recorded sharks moving between the Galápagos and Cocos, 710 km apart, in a median of 33.5 days, and between Malpelo and Cocos, 627 km apart, in a median of 46 days. The schools are part of one population that moves between the islands, which is why protecting each island reserve on its own was never going to be enough.

Malpelo off Colombia is the third island on that circuit and the least settled on timing. Popular accounts split between the first months of the year and the second half; a residency study there recorded dense aggregations followed by a thinning in April and May. It is a liveaboard trip of steep walls and cleaning stations in strong, changeable current, and there is no month we would promise.

All three islands are liveaboard trips of a week or more at sea, and rated for advanced divers because of the current and the open-ocean pickups.

Mexico has two very different seasons. Roca Partida is a bare rock in open ocean, small enough to swim around in one dive, with scalloped hammerheads, oceanic whitetips and Galápagos sharks on every side between November and mid-June, when the liveaboards run. And in the Sea of Cortez, El Bajo is a set of three peaks topping out between 16 and 25 m with nothing showing at the surface. It is where the schooling research began, and it is also the clearest record of what fishing does to them: divers there averaged 150 sharks a dive in the 1970s and about five in the 2010s. Schools are still reported in the northern summer and autumn, and a day boat from La Paz is the cheapest way into the eastern Pacific’s hammerhead water, but go with modest expectations.

Further south, El Faro in Panama’s Coiba reserve drops to almost 30 m in strong current, with hammerheads reported at depth below whitetips and bull sharks. It is a hammerhead possibility rather than a hammerhead dive.

The Atlantic: Bimini, Tiger Beach and El Hierro

Bimini is the exception to everything above. The sharks are great hammerheads, not scalloped; the dive is on open sand at about 6 m (20 ft), not a seamount at 30; and the season is winter, when operators run a dedicated baited encounter that is close to guaranteed. The tagging work gives the widest window, October to March; the operators put the reliable core at December or January through March. It is a long, stationary dive in winter water, so the risk is cold rather than depth. The same study tracked Bimini sharks to Jupiter in Florida and back, and Jupiter runs a great hammerhead season over the same winter months.

Tiger Beach off Grand Bahama is the same idea on a bigger stage: a sand bank in 8 to 10 m where tiger sharks are the headline and lemon, reef, nurse and bull sharks work the same patch, and great hammerheads join them between December and March. Divers kneel in a line on the sand, and the guide sets the bait before anyone else goes in.

Off the Canary Islands, El Bajón is a submarine volcano whose peaks rise to 8 m and whose seaward face falls to 80. Hammerheads are among the pelagics the current brings through, and the local operators are honest about it: if you are lucky. We found no season for them there and would not travel for them alone.

The Red Sea

The Egyptian offshore reefs are the Red Sea’s hammerhead grounds, and they are liveaboard territory. Daedalus Reef is a lone reef 100 km off Marsa Alam, rising from 450 m of water under a lighthouse. Hammerheads first appear there in April, deep. They are shallowest in May and June and go progressively deeper through summer and autumn, so the early-season boats get the closest looks. At Big Brother scalloped hammerheads join oceanic whitetips, greys and threshers on a wall swept by constant current, and Little Brother adds great hammerheads that rise from the deep for a look and drop away again.

Closer to shore, Elphinstone Reef is reached by day boat, and its southern plateau is the end where hammerheads are spotted at depth, early in the morning on an incoming current. Treat them as occasional there rather than seasonal. In the north, Jackson Reef in the Straits of Tiran is the one day-boat hammerhead dive with a season: the sharks appear off the back of the reef in summer, with July and August the months every source agrees on.

Sudan runs on a different clock. At Shaab Rumi, the reef where Cousteau’s Conshelf II habitat still sits on the sand, hammerheads school off the south plateau between November and April, and grey reef sharks hunt the same current. Angarosh Reef is a pinnacle whose name means Mother of Sharks, with plateaus stepping down to 45 m and current strong enough to hold hammerheads and tigers, and Sanganeb Atoll next door has them at 45 m on the Red Sea’s only atoll. The 2023 conflict has disrupted departures from Port Sudan, so check that an operator is running before you plan around it. Further out, Habili Ali at St John’s holds grey reef sharks and hammerheads off an exposed pinnacle, and Djibouti’s Sept Frères pair hammerheads with mantas on current-swept pinnacles near Bab el-Mandeb.

The Indian Ocean and southern Africa

The Maldives has a resident school. At Rasdhoo Madivaru the scalloped hammerheads are there all year, so the hour matters more than the month: the dive is made off the outer wall at first light, dropping past 30 m into open water in current that can be very strong. Far to the south, Farikede is a short, powerful drift over a plateau where hammerheads, threshers, oceanic mantas and mola mola have all come up out of the blue. The island’s operators put the scalloped schools between October and April and at their best from October to December, when the thermocline is shallower, and they note that new and full moon with the right current give the best odds. Tiger sharks are there in every month. In Vaavu, Fotteyo Kandu is a channel drift in strong current where grey reef sharks fill the flow and a hammerhead is something to watch the blue for, not a promise.

Southern Africa’s sites are deep. Northern Pinnacle and Southern Pinnacle in South Africa have reef tops at around 26 to 32 m and drift dives where the current decides the direction on the day. The scalloped schools, often in the hundreds, run in the southern summer from about October to March, and the great hammerheads are most likely around March and April; in winter the same reef belongs to Zambezi sharks. Pinnacles across the border in Mozambique tops out at 28 m and bottoms at 42, and the dive is a hover above the rock followed by a slow ascent watching the blue. Hammerheads are part of its shark list, but we found no season for them separate from the general shark months, and the operator asks for an Advanced certification.

Japan and South-East Asia

Japan has two hammerhead seasons at opposite ends of the year. Mikomoto-shima is a bare rock south of the Izu Peninsula sitting squarely in the Kuroshio, and its operator recommends June to October, when the sea is most settled; it has met hammerheads in every month of recent years, but winter northerlies often keep the boats in. The schools there can run to the hundreds. The current is fierce and the dive is a drift; swimming against it is not an option. Nearly 2,000 km to the south-west, Yonaguni at the end of the Ryukyu chain is a winter dive: the schools gather from about December to April, at their best from January to March, often 100 to 200 animals, at 20 to 40 m in strong current and water of 21 to 23 °C.

Layang-Layang is a Malaysian atoll in the South China Sea where the reef edge drops into 2,000 m of water. At The Point divers leave the reef at 25 to 40 m and watch open water for the schools, and even on shallower wall dives like The Runway hundreds of hammerheads can school in the blue in April and May. Its single resort opened for part of each year, roughly March to August, until Malaysia’s tourism ministry revoked its licence in January 2025; the atoll has been closed to divers since, and no reopening has been announced.

Indonesia’s Batu Gila is a ridge between 28 and 42 m at the extreme northern point of a long reef and the Togians’ best odds on a school. In the Banda Sea, the schools at the offshore seamounts are known from September and October, and at Nutmeg Drop off Run Island hammerheads may patrol the deeper wall in October and November, on a dive otherwise about coral and turtles. At South Point they are rare and deep, passing at 40 m and beyond.

The Philippines has one hammerhead story, and it is changing. Around Malapascua the shark everyone comes for is the thresher, and hammerheads have been reported around the shoals from about January to April; at Monad Shoal they are now one of the reasons the old shoal is still dived. Local operators describe them as occasional, so treat them as a bonus on a thresher trip.

The Pacific and Australia

French Polynesia is great hammerhead country. Tiputa Pass is a lagoon pass drifted on the incoming tide, among the grey reef sharks that fill the channel by the hundred, and a study of the great hammerheads there and at neighbouring Tikehau found most sightings between December and February, spread from November to May. Nearly all the sharks identified were females. Divers saw between one and eleven on a dive, never more than six in the same field of view, and sightings rose towards the full moon, peaking two days before it. Most of them came from a plateau at 45 to 60 m, below recreational limits, so on an ordinary drift a great hammerhead is a lucky pass rather than a sure thing. French sources add that in January, large numbers of stingrays mass in the pass, and the hammerheads feed on them. Tuheiava Pass is the quieter pass, where great hammerheads are logged alongside tiger sharks and mantas.

Palau’s Blue Corner and Australia’s North Horn are shark dives first and hammerhead dives second: the reliable animals are grey reef and silvertip sharks, and at Osprey the park authority records scalloped hammerheads gathering off the walls in the cooler months. In Fiji’s Bligh Water, seamounts like Mount Mutiny produce single hammerheads and small groups at recreational depth; the big schools there have been filmed only by technical divers, far below it.

South West Rocks in New South Wales is the southern outlier. At Larry's Ledge off Fish Rock, divers settle on a flat ledge at about 14 m, often sheltered from the current, and in the warmer months hammerheads patrol the water off it. A school of around 200 is sometimes seen from October to January, and November to January is the stretch to target, usually above 20 m and away from the rock in current. It is the one dive in this guide where even a keen writer on the site admits to never having seen them, so book it for the grey nurse sharks and count any hammerhead as luck.

How to dive with them

Hammerhead dives fail for the same few reasons everywhere, and none of them is bad luck.

Timing. The schools are closest at first light and at cleaning stations. Rasdhoo is a dawn dive, and Elphinstone’s southern plateau is best early. If the boat offers a pre-breakfast dive, that is the one.

Depth. Scalloped schools hold deep, often below the thermocline, and every site in this guide is easy to overshoot. Manuelita’s cleaning stations are at 30 to 35 m, Protea’s reef top is at 26 m or deeper, and Rangiroa’s hammerhead plateau is below recreational limits altogether. Bottom time at that depth is short, the sharks are usually deeper than the plan, and a school in view is exactly the moment you stop watching your computer. Agree a turn depth on the boat and check it more often than you would on a reef.

Current. Current is why the sharks are there, and it is also why most of these sites are rated advanced. The technique is the same from Darwin to Daedalus: negative descent, get onto the rock, stay low and hold position rather than swim. Carry a surface marker buoy and expect to be picked up in open water.

Noise and bubbles. Hammerheads are shy of divers. Groups that hang quietly at the ledge see schools; groups that chase see tails. Breathe slowly, stay still, and let the school come to the rock rather than swimming out to meet it.

Baited dives. On the great hammerhead dives at Bimini and Tiger Beach the rules are the guide’s, and they are the opposite of chasing: stay in the line on the sand, keep hands and camera in close, and let the shark decide the distance.