Hammerhead schools, tiger sharks and the legendary Cocos Island — Pacific big-animal diving at its peak.
Costa Rica's liveaboard scene revolves around Cocos Island, a UNESCO World Heritage Site 550 km off the Pacific coast. Reachable only by liveaboard, Cocos is one of the planet's top three pelagic destinations: massive schools of scalloped hammerheads, silky and Galápagos sharks, mobula rays, marlin and seasonal whale sharks. Trips run 8–10 days due to the 32–36 h crossing.
June–November is widely considered the best window: stronger plankton blooms, cooler water (24–26 °C) and the largest hammerhead aggregations. December–May offers calmer seas and better visibility (20–30 m) but smaller schools. Whale sharks peak August–October.
Juan Santamaría International Airport (SJO) in San José is the main gateway, with direct flights from most North American hubs and several European cities. Liveaboards depart from Puntarenas on the Pacific coast — a 1.5 h transfer from San José (usually included).
Puntarenas is the only departure port for Cocos itineraries. Boats must be ocean-class to handle the open-Pacific crossing.
Bajo Alcyone is the iconic hammerhead cleaning station. Manuelita Coral Garden and Manuelita Outside offer reliable shark action close to the island. Dirty Rock and Dos Amigos are famous for tiger sharks and large schools. Everest is a deep submerged seamount for advanced divers.
Advanced certification + 50 logged dives is the practical minimum (some operators require 100). Bring a 5 mm wetsuit, gloves, a hood, a torch and an SMB with reel. The crossing can be rough — pack motion-sickness medication.
Spanish is the official language but English is widely spoken. Currency is the colón (CRC); USD is accepted everywhere. Power is 120 V/60 Hz (US plugs). Costa Rica is on UTC−6.
The crossing to Cocos takes 32–36 hours each way and seas can be rough. Currents at Cocos sites are strong and unpredictable — strict adherence to dive briefings is mandatory. The nearest chamber is in Puntarenas; in-water evacuation is impossible. Comprehensive dive and trip-cancellation insurance is essential.
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