Few places on earth have such an enormously rich marine life as does Isla del Coco, an uninhabited tropical island that lies 500 kilometres southwest of Costa Rica. It is best known as Treasure Cove Island.

The first pirates came here during the 17th century to rejuvenate themselves and gather supplies in preparation for their next pirate raid along the South American coast.

According to an enduring legend, the pirates also have hidden gold and precious stones worth hundreds of millions of pounds on this very island.

However, none of the 500(!) known treasure expeditions have ever found so much as one gold doubloon. The real treasure is the ocean around the island. In the warm, shimmering, turquoise waters live a sanctuary of animals and plants, which, in many cases, are endemic and only exist here around Isla del Coco.

“There is nothing to compare to this,'' says underwater photographer Jay Ireland, who, for 30 years, has dived in places all over the world. “Coco is for me No 1. There is nowhere else I have swum around as amazing as this place''.

We met hundreds of hammerhead sharks, whale sharks, giant manta rays, sea turtles and dolphins during just one dive! There is an unrivalled range of species here and the most surprising is the sheer number in which they exist.

Hammerhead sharks in full force

Isla del Coco is one of the few places in the world where hammerhead sharks assemble in the thousands. They come here along with other large ocean living species, such as whale sharks and giant manta rays, to let themselves be cleansed of reef fish.

Most dives are also done near these cleaning stations, which often lie 30-40 metres below the surface. It is here that hammerhead sharks stop to let small fish clean away parasites and dead tissue.

Scientists also believe hammerhead sharks are drawn to the island to breed and that can be why they gather in such large flocks.

Another theory is that Isla del Coco is a halfway point during their wandering in the Pacific Ocean. Because the island is a national park, certain divers live on-board the boat during the ten-day trip.

Fearless mantas

The actual diving takes place from Zodiacs or small aluminium boats. The number of divers on every boat is usually 20 and normally there are three dives a day.

Those who are not worn out after three dives are even offered a night dive.

Of course, it is exciting to experience Isla del Coco as an old pirates' island. All that fades away, however, the minute you enter the water.

During one of my dives with my diving partner, Randy Johnson from Alaska, nicknamed “Ice Man'', we were approached by 12 large mantas right near the surface.

We adapted our weights and hung motionless just under the surface while they calmly swam under, over and between us at just a few inches' distance from us.

We could clearly see traces of parasites on their bodies, small sores and even, swimming around them, the reef fish which helped to heal the mantas sores. That dive was worth more than any treasure of gold!

When we later came up to the surface, we were told by the driver of our Zodiac that mantas often follow the rubber boats and like to hold themselves close to them.

The island lies five degrees north of the Equator, so a thin suit is enough to keep warm. Divers who expect warm tropical diving with corals will be disappointed.

Most of the coral was carried away in 1982-83 by El Nino, a warm ocean current which, with regularity, pulls in towards the South American coastline.

For visitors, Isla del Coco is an oasis both under the surface and on land. The pirates have, of course, left the island but the priceless wealth of flora and fauna is still remaining and possibly a few gold doubloons.

— Frank Stenstrom is a freelance writer based in Sweden

By Frank Stenstrom, Special to Explore

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