All activities / Scuba Diving / Cocos Island
ReasonToGo · activity-first travel discovery. Honest timing. No bookings, no commissions, no one pays to rank. How we choose →
Scuba Diving in Cocos Island
A UNESCO World Heritage Site 550km southwest of Costa Rica, accessible only by liveaboard. Schooling hammerheads, whale sharks, and manta rays in open-ocean conditions. For experienced, dedicated divers only.
Why here
The world's premier destination for schooling hammerheads. No accommodation, no day visitors, liveaboard only, 36 hours offshore. The payoff is underwater encounters that have no equivalent in the Pacific: walls of hammerheads at Dirty Rock and Alcyone, whale sharks on almost every dive, silvertip and Galapagos sharks throughout. A UNESCO World Heritage Site with strict permit limits that keep it genuinely pristine.
Best months
Visibility 10-20m, plankton-rich water feeds the pelagics, so murky water is correct. Water temp 22-27°C with significant thermoclines (18°C not uncommon below 20m, 5/7mm wetsuit or semi-dry required). Strong surge and currents at all sites, open-water experience essential. Dirty Rock and Alcyone: hammerhead schools from 15-40m, most reliable Jun-Oct. Manuelita: night dive with whitetips and nurse sharks. Tiger sharks and silvertips common throughout.
Getting there & around
Liveaboard only, no exceptions. Fly to San Jose, Costa Rica, then bus or transfer to Puntarenas (2-3 hours). Sea crossing: 30-36 hours each way. 7-10 night trips are standard. Very limited park permits, book 6-18 months in advance. Undersea Hunter Group and Okeanos Aggressor are the primary operators. Cost: $4,500-6,500+ per person. For dedicated, experienced divers only.
Skill levels: advanced
Schools & guides (3)
Nautilus Cocos Undersea
OutfitterCanadian-operated liveaboard offering Cocos Island expeditions with a strong conservation focus. 10-day itineraries from Puntarenas. Expert guides with extensive knowledge of Cocos' shark highways, manta aggregations, and schooling jacks.
Okeanos Aggressor
OutfitterPart of the Aggressor Adventure Fleet, one of the original Cocos Island liveaboard operators. Runs 10-day itineraries departing Puntarenas with exclusive access to Cocos' shark aggregation sites: Dirty Rock, Alcyone, and Manuelita. Encounters with scalloped hammerheads, silkies, whale sharks, and mantas.
Undersea Hunter
OutfitterThe original Cocos Island liveaboard operator, running the Sea Hunter and Argo from Puntarenas. Refitted commercial fishing vessels with specialist stabilising technology and large dive platforms. 8-10 day itineraries to Cocos with up to 4 dives per day.
Also good for scuba diving in September:
Torn between Cocos Island and Galapagos Islands for September?
A plan settles it for your skill and budget, same-day.