Peak Jun–Nov
Scalloped hammerhead
Present all year and densest in the wet season, June to November (Liveaboard.com), in schools over Bajo Alcyone and at the cleaning stations (DAN).
514marine fish species recorded (Fourriére et al. 2016)
3land birds found nowhere else (UNESCO)
200+hammerheads reported in one school (SEE Turtles 2024)
~55,000 km²of fully protected ocean since 2021 (Mission Blue)
Why Cocos
Cocos is a small, steep volcanic island of about 24 km², roughly 550 km southwest of mainland Costa Rica (Wikipedia). It has been a national park since 1978 and a UNESCO World Heritage Site since 1997, extended to the surrounding sea in 2002 (UNESCO; Wikipedia). In 2021 Costa Rica added about 53,000 km² of fully protected water, bringing the park to about 55,000 km² (Mission Blue).
The island sits on a migration corridor that links it with the Galápagos, and its seamounts gather hammerheads, other sharks, rays and big schools of jacks (Mission Blue; DAN). It is reached only by liveaboard, a crossing of 30 hours or more that can be rough. Diving is intermediate to advanced, with strong currents, surge and sharp thermoclines; it is not a destination for new divers (DAN).
Location
Where the sites are
The sites named under “What divers report”, around the island and its islets.
Dive sites around the island
Dive sites, clockwise from Manuelita
- 1Manuelita
- 2The Channel
- 3Submerged Rock
- 4Big and Small Dos Amigos
- 5Punta María
- 6Dirty Rock
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The site map works offline and prints. Satellite is interactive: zoom and drag, and tap or hover a pin for its name (it needs an internet connection). Positions are approximate. Alcyone and Silverado are not on published charts, so they have no pin. Site positions: NGA GeoNames. Coastline © OpenStreetMap contributors.
Choose your dive
Five field pages, with where and when to look for each species and links to go deeper.
When the big animals come
Pick a month to see which big animals are at their peak. The dry season runs January to June; July to December is the rainy season, with rougher seas and cooler water (DAN). Check season and conditions with your operator before booking.
Peak Aug–Oct
Whale shark
Most likely from August to October (Liveaboard.com), and reported at Alcyone more than at any other site (DAN).
Peak Dec–May
Mobula and manta rays
Mobula rays are more likely in the dry season, December to May (Liveaboard.com). Mantas make occasional fly-bys at Manuelita (DAN).
Photo Megan Applegate (Cocos Island)
Six to know by sight
The sharks and rays most often reported here, with the mark that gives each away. The Sharks & rays page has the full notes and sources.
Plate I
Scalloped hammerhead
Sphyrna lewini
- Look for
- A hammer-shaped head with a scalloped front edge and a notch in the middle.
- At Cocos
- All year, densest Jun–Nov. Schools over Bajo Alcyone; cleaning stations at Dos Amigos at about 30 m.
Plate II
Whitetip reef shark
Triaenodon obesus
- Look for
- Small and slim, with white tips on the first dorsal and the upper tail lobe.
- At Cocos
- The most common shark here. Rests by day at Submerged Rock; hunts in packs at night at Manuelita.
Plate III
Galápagos shark
Carcharhinus galapagensis
- Look for
- Stocky and plain grey-bronze, with a broad rounded snout and a tall, upright first dorsal.
- At Cocos
- Close passes at the cleaning stations of Dirty Rock and Punta María.
Plate IV
Silky shark
Carcharhinus falciformis
- Look for
- A tiny second dorsal fin with a long, thin trailing tip, and long sickle-shaped pectorals.
- At Cocos
- Occasional, at Manuelita, Dirty Rock and Bajo Alcyone.
Plate V
Tiger shark
Galeocerdo cuvier
- Look for
- A large shark with a blunt, square snout; dark vertical stripes on younger animals.
- At Cocos
- Reported more often in recent years, along the sandy edges of the reefs and at Manuelita.
Plate VI
Giant oceanic manta
Mobula birostris
- Look for
- The largest ray, with a wingspan up to about 7 m. Visits cleaning stations.
- At Cocos
- Occasional fly-bys at Manuelita.
What divers report, site by site
From DAN, Blue Water Dive Travel and SEE Turtles. Individual dives vary.
Manuelita
Shallow and calm, with dozens of whitetips, frogfish, turtles and marbled rays; cleaning stations on the steep back side.
Source: DANManuelita at night
Dozens to hundreds of whitetips hunting together over the reef.
Source: DAN; Blue Water Dive TravelDirty Rock
Cleaning stations visited by hammerheads, silkies and Galápagos sharks; tuna and dolphins on bait balls.
Source: DANAlcyone
An offshore seamount at about 27 m with strong current: hammerhead schools, silkies, horse-eye jacks, and the best chance of a whale shark.
Source: DANPunta María
A seamount rising to about 23 m, with close passes by Galápagos sharks and hammerheads, trevally and snapper.
Source: DANSubmerged Rock
A truck-sized swim-through at about 21 m, often full of sleeping whitetips.
Source: DANBig and Small Dos Amigos
Hammerhead cleaning stations at about 30 m; an arch at Big Dos Amigos often holds large marbled rays.
Source: DANSilverado
A rock rising to about 5 m above a sandy slope: silvertip sharks, the Cocos batfish, jawfish and snake eels.
Source: DANThe Channel
Eagle rays ride the current between Cocos and Manuelita.
Source: SEE Turtles 2024Photos
Photos marked “Megan Applegate” were taken at Cocos Island in August 2024, except a few fish and bird photos from Malpelo, which are labelled on their pages. The rest come from the sources credited on each page.
Photo Megan Applegate (Cocos Island)
More information
Every link opens in a new tab.
- UNESCO World Heritage — Cocos Island National Park
- Wikipedia — Cocos Island
- DAN Alert Diver — Cocos Island: the pelagic crossroads, with site descriptions
- Liveaboard.com — best time to dive Cocos Island
- Blue Water Dive Travel — Cocos Island trip report
- SEE Turtles — Cocos expedition 2024 log, part 2
- SEE Turtles — Cocos expedition 2024 log, part 3
- SEE Turtles — Cocos expedition 2024 log, part 4
- Mission Blue — Costa Rica adds nearly 53,000 km² to the park (2021)
- Fourriére et al. 2016 — checklist of the marine fishes of Cocos Island
- Dive The World — Cocos Island National Park
- Oceanlight — Cocos Island photos