Cocos Island

Cocos lies more than five hundred kilometres out in the Pacific, uninhabited except for park rangers, wrapped in rainforest and streaming with waterfalls that fall directly into the sea. Jacques Cousteau called it the most beautiful island in the world, and it is widely thought to have inspired the setting of Jurassic Park. Nobody goes for the land, though; you cannot stay ashore. The draw is underwater, where seamounts and currents concentrate marine life on a scale that has few equals: scalloped hammerheads in schools of hundreds at cleaning stations, whitetip reef sharks hunting in packs at night, mantas, marbled rays, tuna, dolphins and, in season, whale sharks. It is diving for people who have already done a great deal of diving.

What you actually see

• Bajo Alcyone - the seamount where hammerhead schools gather at the cleaning stations.
• Manuelita - night dives with whitetip reef sharks hunting in packs across the reef.
• Dirty Rock - big pelagic action in current, one of the signature sites.
• The island itself - waterfalls falling into the sea, seen from the boat.

When to go

June to November is the rainy season on the island and the best time for hammerhead aggregations, with rougher seas. December to May brings calmer crossings and better visibility but fewer big schools.

Honest expectations

This is expensive, remote and physically demanding: over a day of open ocean each way, strong currents, cold thermoclines and dives that require real experience. Most operators set a minimum number of logged dives, and advanced certification is effectively mandatory. Seasickness on the crossing is common. Landing is limited to ranger-supervised visits, so this is a boat and water trip only.

Nearby

Puntarenas is the mainland port; the Osa peninsula and Corcovado are the closest wild coast.