Cocos Island
Costa Rica · Eastern Pacific
Cocos Island sits 550km off the Pacific coast of Costa Rica — a rainforested rock surrounded by deep water and one of the planet's great shark aggregations. Schooling scalloped hammerheads, Galápagos sharks, silkies, tigers (occasional), tuna, marbled rays and resident dolphins. Liveaboard-only, with a 30–36 hour crossing each way.
How this reef is doing
ⓘ How we measure thisReef state
Reef fish biomass inside this fully protected park averages 7.8 tonnes per hectare, among the highest in the tropics and nearly 40% apex predators (Friedlander et al. 2012); long term monitoring shows some shark and ray species declining, so the state here stays measured rather than improving.
Coral cover
Fish life
More fish than a healthy reef of its kind.
Heat
Warmer than usual right now, but not hot enough to bleach.
Fishing
Quiet water, and fishing is fully banned here.
Sources · MERMAID and partner coral surveys · Reef Life Survey · NOAA Coral Reef Watch · Global Fishing Watch and reef gravity
Fish abundance
Fish seen per survey
Across 8 years of REEF volunteer surveys around Cocos Island, divers have recorded a steady amount of fish per survey. This tracks fish life, standardised for survey effort, so we keep it separate from the coral read above.
Fish abundance over time
| Year | Density index | Surveys |
|---|---|---|
| 2003 | 2.38 | 44 |
| 2007 | 2.40 | 19 |
| 2008 | 2.14 | 10 |
| 2010 | 2.48 | 26 |
| 2014 | 2.19 | 21 |
| 2018 | 2.43 | 19 |
| 2020 | 2.42 | 21 |
| 2023 | 2.45 | 21 |
What you will see
15 species across the dive sites here
Guineafowl Puffer
Seen 3 months ago
at Bajo Alcyone
Least concern
Scalloped hammerhead
Seen 3 months ago
at Bajo Alcyone
Critically endangered
Bigeye trevally
Seen 5 months ago
at Dirty Rock (Roca Sucia)
Least concern
Marble ray
Seen 5 months ago
at Manuelita Island
Mexican Hogfish
Seen 5 months ago
at Bajo Alcyone
Least concern
Whitetip Reef Shark
Seen 5 months ago
at Bajo Alcyone
Vulnerable
Barberfish
Seen 5 months ago
at Dirty Rock (Roca Sucia)
Least concern
Marbled ray
Seen 5 months ago
at Dirty Rock (Roca Sucia)
Vulnerable
Galapagos shark
Seen 5 months ago
at Bajo Alcyone
Least concern
Cocos Wrasse
Seen 5 months ago
at Bajo Alcyone
Vulnerable
Silvertip shark
Seen Dec 2024
at Bajo Alcyone
Vulnerable
Manta ray
Seen Jan 2024
at Manuelita Island
Endangered
Green turtle
Seen year round
at Dos Amigos Grande
Least concern
Tiger shark
Seen year round
at Manuelita Island
Near threatened
Whale shark
Seasonal visitor
at Bajo Alcyone
Endangered
Dive sites
Bajo Alcyone
scalloped hammerhead · galapagos shark · whale shark · silvertip shark
Dirty Rock (Roca Sucia)
scalloped hammerhead · galapagos shark · whitetip reef shark · marbled ray
Manuelita Island
scalloped hammerhead · whitetip reef shark · tiger shark · galapagos shark
Dos Amigos Grande
scalloped hammerhead · whitetip reef shark · galapagos shark · marble ray
What divers say
Two days at sea, then four days of the heaviest shark traffic I've ever seen, then two days back. Worth every hour.
Good to know
Crossing
32–36h each way from Puntarenas. Bring scopolamine.
Park fee
~$500 conservation fee on top of trip cost.
No land diving
There's no infrastructure on the island for divers — it's a national park visit only.