Cocos Island (Spanish: Isla del Coco) is a volcanic island in the Pacific Ocean. It is managed by Costa Rica and located about 550 km (342 miles) southwest of the Costa Rican mainland. The island is part of the 11th district in the Puntarenas Canton of the Puntarenas Province. It has an area of about 23.85 km² (9.21 square miles) and is shaped roughly like a rectangle. It is the southernmost point of North America if non-continental islands are included, and it is the only land above water on the Cocos tectonic plate.

Cocos Island has been a Costa Rican National Park since 1978. No one lives there permanently except Costa Rican park rangers. Although some sources once claimed it was the largest uninhabited island in the tropics, this is incorrect because the island of Fernandina in the Galapagos archipelago is also uninhabited and much larger. The island is surrounded by deep ocean waters with strong currents, making it a popular spot for scuba divers who come to see hammerhead sharks, rays, dolphins, and other large marine animals. The island’s wet climate and ocean conditions create an ecosystem that is different from the Galápagos Archipelago and other islands, such as Malpelo, Gorgona, or Coiba, in the eastern Pacific Ocean. Because of its unique environment, Cocos Island National Park was named a UNESCO World Heritage Site in 1997. The island can only be reached by boat, which usually takes 36 to 48 hours.

History

The island is thought to have been without human inhabitants before Europeans arrived. However, there have been few studies by archaeologists looking into the oceanic islands of the eastern Pacific, including Cocos Island. This is because these islands have delicate environments that were not touched by humans for many years and are far from places where Polynesians lived. Also, Indigenous people on the west coast of the continent were not known to live on remote eastern Pacific islands. In 2008, archaeologists from the Australian National University studied Cocos Island, the Desventuradas Islands, Galápagos Islands, and Juan Fernández Islands. These islands were not inhabited when Europeans discovered them. Their research suggested that the Galápagos Islands might have been visited by a Polynesian ship, but the findings about Cocos Island remain unclear.

In his book Historia general y natural de las Indias (1535, expanded in 1851), Gonzalo Fernández de Oviedo y Valdés wrote about the discovery of the island by Juan de Cabezas (also called Juan de Grado), a Spanish navigator, in 1526. A document titled Una isla desierta en el Pacífico; la isla del Coco (1962: 134) mentions that the first map with the name "Isle de Coques" appeared in 1542 during the reign of Francis I of France. A map by Nicolas Desliens from 1556 (Dieppe) shows the island about one and a half degrees north of the Equator.

Willem Blaeu’s Grand Atlas (1662) includes a map showing I. de Cocos on the Equator. Frederik De Witt’s Atlas (1680) shows the same. The Hondius Broadside map of 1590 places I. de Cocos at 2 degrees and 30 minutes north latitude. In 1596, Theodore de Bry showed the Galápagos Islands near 6 degrees north of the Equator. Emanuel Bowen’s A Complete system of Geography (1747: 586) states that the Galápagos Islands stretch 5 degrees north of the Equator.

James Colnett, who surveyed eastern Pacific islands for British whaling interests, visited Cocos Island in 1793 and collected 2,000 coconuts. He left a boar, a sow, and a male and female goat on the island. George Vancouver arrived two years later and anchored his ships Discovery and Chatham in what is now called Chatham Bay. He took water, wood, and many coconuts. Before leaving, he carved the date of their arrival and the names of the ships and their commanders into a rock, joining an existing inscription. Both Colnett and Vancouver published maps in 1798. Colnett’s maps included a "Plan of the Island Cocos," and Vancouver’s map of the Sandwich Islands (Hawaii) had an inset of Cocos Island. Captain Edward Belcher anchored at Chatham Bay in 1838 and noted that whalers had cut down most of the trees for fuel. He added his ship’s name to the growing list of inscriptions.

Before the 20th century, scientific research on oceanic eastern Pacific islands was limited, except for the Galápagos Islands. In 1891, The American Naturalist wrote, "we know nothing at all about the animals and plants of the isolated Clipperton Island and Malpelo; we hardly know anything about Cocos Island, which seems to be in many respects quite different from the others, having a more tropical appearance."

Cocos Island was annexed by Costa Rica in 1832 through decree No. 54 by the Constitutional Assembly of the newly independent country. During the 1830s and 1840s, whalers stopped at Cocos Island for water and wood until whaling moved to other parts of the Pacific.

In October 1863, the ship Adelante left 426 Tongan former slaves on the island after discovering they had smallpox and were a danger to the crew. When the ship Tumbes arrived to rescue them a month later, only 38 survivors remained, as the rest had died from smallpox.

In 1897, the Costa Rican government named August Gissler, a German adventurer and treasure hunter, the first governor of Cocos Island and allowed him to create a short-lived colony there.

On May 12, 1970, Cocos Island became an administrative district of Puntarenas canton in the Puntarenas Province through Executive Decree No. 27. As a district, the island has the postal code 60110.

The island’s 33 residents, all Costa Rican park rangers, were allowed to vote for the first time in Costa Rica’s February 5, 2006, election. However, the rangers are not considered permanent residents, so census data lists the island as uninhabited.

Cocos Island has appeared in many pirate stories and treasure legends. One claim came from Mary Welch, who said 350 tons of gold (about $16 billion today) stolen from Spanish ships was buried on the island by Captain Bennett Graham, a pirate who became a naval officer in 1818. Welch was part of Graham’s pirate crew and was sent to an Australian penal colony. After her release, she returned to the island with an expedition but failed to find the treasure, as the landmarks on her map were gone.

Another pirate, Benito Bonito of Portugal, is said to have hidden treasure on the island around 1818. Though Bonito was captured and executed, his treasure was never found.

One of the most famous treasure stories involves the "Treasure of Lima." In 1820, as José de San Martín’s army approached Lima, Viceroy José de la Serna is said to have given treasure to British trader Captain William Thompson for safekeeping. Instead of waiting, Thompson killed the viceroy’s men and sailed to Cocos Island, where he allegedly buried the treasure. Later, Thompson and his crew were captured by a Spanish warship. Thompson and his first mate promised to show the Spaniards where the treasure was hidden, but they escaped into the forest and were never found.

Many attempts to find treasure on the island have failed. Some early expeditions were based on claims by a man named Keating, who supposedly knew Thompson. Keating reportedly found gold and jewels, but others, like German adventurer August Gissler, only found a few coins. British explorer Aeneas Mackintosh led a treasure hunt in 1910 but found nothing.

Cocos Island was declared a Costa Rican National Park in 1978 and a UNESCO World Heritage Site in 1997. In 2002

Geology and landscape

Cocos Island is an oceanic island formed by both volcanic activity and tectonic plate movements. It is the only land area of the Cocos Plate, one of the smaller tectonic plates. Scientists used potassium–argon dating to determine that the oldest rocks on the island are between 1.91 and 2.44 million years old. The island is mostly made of basalt, a type of rock created when lava cools. Cocos Island is the visible top of a shield volcano from the Pliocene and Pleistocene eras, located along the central part of the aseismic Cocos Ridge. Inside the island’s caldera is a lava dome made of trachytic rock. The most recent volcanic activity on the island came from fissures that ran in a northeast direction, producing lava flows.

The island is roughly rectangular, measuring about 8 km × 3 km (5 mi × 2 mi) with a perimeter of around 23.3 km (14.5 mi). Its landscape is mountainous and uneven, with the highest point being Cerro Iglesias at 575.5 m (1,888 ft). Despite its mountains, there are flatter areas in the island’s center, between 200–260 m (660–850 ft) in elevation, which are considered a transitional stage in the geomorphological cycle of V-shaped valleys.

Cocos Island has several short rivers and streams that carry rainwater into four bays, three of which are on the north side (Wafer, Chatham, and Weston). The largest rivers, Genio and Pittier, flow into Wafer Bay. The island is surrounded by steep cliffs that are 90 meters (300 ft) high, making access difficult except at a few beaches. The easiest place to enter the island is at Chatham Bay. The combination of mountains and a tropical climate creates over 200 waterfalls across the island. The island’s soils are classified as entisols, which are very acidic and would erode easily from heavy rainfall on steep slopes if not for the dense forest coverage.

Cocos Island has a tropical rainforest climate (Köppen: Af), similar to the Colombian Chocó region. This climate is influenced by the Intertropical Convergence Zone, which causes frequent cloudiness and rain throughout the year. Like the Chocó, the North Equatorial Countercurrent from the central Pacific Ocean brings warm, rainy conditions to the island. The average annual temperature is 26.6 °C (79.9 °F), and the average yearly rainfall exceeds 7,000 mm (276 in), comparable to areas like Andagoya or Buenaventura. Rainfall remains high all year, though it is slightly lower from January through March and again during late September and October.

Ecology

Cocos Island is covered with thick tropical moist forests. It is the only oceanic island in the eastern Pacific with these types of rainforests and their special plants and animals. The cloud forests at higher elevations are also unique in the region. The island was never connected to a continent, so its plants and animals arrived from the Americas through long-distance travel. This has led to many species found only on Cocos Island.

The island has 235 known flowering plant species, 70 of which are found nowhere else. A detailed study about the island’s plants was published in the Proceedings of the California Academy of Sciences. Other reported species include 74 ferns and related plants, 128 mosses and liverworts, 90 fungi, and 41 slime molds. More research is expected to find even more species.

The island has three main plant communities. Coastal forests grow from the shore up to 50 meters (160 feet) high. Trees like the purple coral tree (Erythrina fusca), coconut palm (Cocos nucifera), and pond-apple (Annona glabra) are common. These forests also have ferns, shrubs, sedges, grasses, and plants from the Leguminosae and Malvaceae families.

Inland forests cover elevations from 50 to 500 meters (160 to 1,640 feet). Trees such as Sacoglottis holdridgei (called "palo de hierro" or "huriki"), Ocotea insularis (called "avocado"), and the endemic Cecropia pittieri are dominant. These trees are covered with epiphytic plants like orchids, ferns, bromeliads, and mosses. The understory includes sedges like Hypolitrum amplum, ferns, tree ferns such as Cyathea armata and Danaea media, and the palm Euterpe precatoria. Cloud forests, where Melastoma species are common, are found above 500 meters (1,600 feet).

The island’s vegetation has changed since Europeans first visited it. Captain Wafer, who explored the island in 1685, described large coconut groves extending inland. Thor Heyerdahl suggested these groves were not natural and that early humans may have cleared land for coconut plantations to support voyages between Guatemala and South America. After European colonization, these plantations were abandoned, and the jungle grew back. However, no clear evidence of early human habitation has been found.

Over 400 insect species live on the island, 65 of which are unique to Cocos Island. The most diverse groups are Lepidoptera (butterflies and moths) and Formicidae (ants). More than 50 other arthropods, such as spiders, centipedes, millipedes, and isopods, have also been identified.

Two lizard species live on the island: the Cocos Island anole (Anolis townsendi) and the Pacific least gecko (Sphaerodactylus pacificus). Both are endemic. No amphibians have been reported.

Nearly 90 bird species are present. Large nesting colonies of migratory seabirds, such as the Cocos booby (Sula brewsteri), red-footed booby (Sula sula), great frigatebird (Fregata minor), white tern (Gygis alba), and brown noddy (Anous stolidus), live on the island and nearby rocks. Seven land bird species are found on the island, including three endemics: the Cocos cuckoo (Coccyzus ferrugineus), Cocos flycatcher (Nesotriccus ridgwayi), and Cocos finch (Pinaroloxias inornata). The Cocos finch is the only member of its genus. The island is designated an Important Bird Area by BirdLife International.

No native land mammals live on the island, but humans have introduced pigs, deer, goats, cats, and rats. These animals harm the local ecosystem by eating native plants or hunting native animals, so efforts are underway to control them.

The island’s surrounding waters and volcanic features are home to over 30 coral species, 60 crustaceans, 600 mollusks, and more than 300 fish species. These include yellowfin tuna (Thunnus albacares), giant mantas (Manta birostris), sailfish (Istiophorus platypterus), and sharks like the whitetip reef shark (Triaenodon obesus) and scalloped hammerhead shark (Sphyrna lewini). The whale shark (Rhincodon typus), the largest fish species, also lives there. In December 2017, a tiger shark killed a diver in the Isla del Coco National Park.

Other marine animals include humpback whales (Megaptera novaeangliae), orcas (Orcinus orca), pilot whales (Globicephala macrorhynchus), bottlenose dolphins (Tursiops truncatus), and sea lions (Zalophus californianus).

Reptiles such as hawksbill turtles (Eretmochelys imbricata), green turtles (Chelonia mydas), and olive ridley turtles (Lepidochelys olivacea) also live on the island.

Despite its untouched habitats, the island faces growing human pressures. Illegal hunting of large marine species in its protected waters is a major concern. Demand for tuna, shark fin soup, and other seafood threatens the island’s ecosystems. The Costa Rican government has been accused of failing to protect the area and profiting from illegal trade. While some efforts to protect the island have been made, challenges like limited funding, bureaucracy, and corruption hinder progress.

Recent events show that illegal hunting continues. Poachers caught with evidence have often been released quickly, and efforts to fund protection have been insufficient. A local judge, Marvin Orlando Cerdas, allowed 22 poachers to leave the country. A district attorney, Michael Morales Molina, stopped the auction of confiscated goods after a request from the captain of an illegal poaching ship. These events highlight ongoing challenges in enforcing environmental laws.

In fiction

The book Desert Island suggested a detailed idea that Daniel Defoe used Isla del Coco as a real-life example for describing the island where Robinson Crusoe lives in his story. However, Defoe placed Crusoe’s island not in the Pacific Ocean, but in the Atlantic Ocean, near the coast of Venezuela.

A color map by Joannes Jansson from Amsterdam shows the northeastern part of South America. The map is titled Terra Firma et Novum Regnum Granatense et Popayan and was printed around 1630 by Willem Blaeu. The area called Terra Firma on the map refers to the Isthmus of Darien.

Stories about pirates and hidden treasure connected to the island are believed to have inspired Robert Louis Stevenson’s novel Treasure Island.