Diving Cocos Island, Costa Rica

Perennially ranked in the top 5 locations to dive in the world, Cocos Island of Costa Rica are part of the same nutrient rich ‘golden triangle’ as the Galapagos and Malpelo islands. Lying 500km and 36 hours from the marina of Puntarenas in mainland Costa Rica, the journey to the islands can be an arduous day and a half ocean crossing, however the underwater mecca that awaits is well worth the trip.

Cocos Island, filmed for Jurassic Park and declared a marine national park in 1978 is uninhabited apart from a handful of park rangers, for this reason there is no airport on the island and only two dive operators, Aggressor and Undersea Hunter facilitate divers who want to dive the Island.  Due to the fact that the 20 dive sites are all in a compact location, situated close to the island from walls to pinnacles to deep blue dives and shallow sandy bottoms Cocos Island is a liveaboard dream.

The seasons at Cocos can be temperamental due to the convergence of two equatorial weather patterns. Where as weather temperatures average 25 degrees Celsius (77 Fahrenheit), the annual precipitation is extremely high with over 6 feet of rain falling on the island.

Calmer seas and higher visibility tend to be between December and May, where visibility can be as high as 30 metres (100 feet), despite this the diving is sensational all year round, in fact especially during the wet season where hammerhead numbers tend to be slightly higher, and the chance to encounter manta rays and whale sharks increases due to nutrient rich upwelling’s.

While the water temperature is always high, averaging a barmy 27 degrees Celsius (83 Fahrenheit) vicious thermoclines can lower the temperature substantially. Most divers tend to dive with a 5mm or a 7mm due to long dives and sudden changes in temperature.

Due to heavy current and surge divers must be advanced especially as the main attraction of Cocos are the plethora of sharks that inhabit the waters of the island. Hammerheads, Whitetip, Galapagos, Whale, Thresher, Silky, Tiger, Silvertip and Bull are some of the species that can be encountered. Furthermore other species of ray, whale and dolphin can be seen cruising in the pelagic waters while vortexes of jacks twirl in the blue.


The famed hammerhead dive of Cocos Island, Bajo Alcyone is a pinnacle a mile off the coast of the island. A negative descent through strong current to 26 metres (90 feet) is where the action begins. Cling to the pinnacle and marvel as up to 500 hammerheads fill your vision as they sweep over the pinnacle. Hammerheads are not the only shark species that frequent the pinnacle, whale, silky and the occasional Galapagos shark have also been spotted.


Just as popular as Bajo Alcyone, Dirty Rock is known for its vortex of jacks where divers are often lost for seconds in the middle of these fish. Mantas are known to glide around the pinnacle while shark species flood the channel that divides the island and the pinnacle.

In Summary

If you are up for the journey to the island, you will most certainly be rewarded with a diving trip of a lifetime. If you have tried out the Catalina Islands and the Bat Islands of Costa Rica, this is a great location to cross off some bucket list quality diving!

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