Cocos Island (Spanish: Isla del Coco) is an island located off the shore of Costa Rica. It constitutes the 11th district (one of 13) of Puntarenas Canton of the province of Puntarenas. It is one of the National Parks of Costa Rica. It is located at 05°31′08″N 087°04′18″W / 5.51889°N 87.07167°W / 5.51889; -87.07167. With an area of approximately 23.85 km² (9.2 mi²), about 8×3 km (5×1.9 mi) and a perimeter of around 23.3 km this island is more or less rectangular in shape.

Surrounded by deep waters with counter-currents, Cocos Island is admired by scuba divers for its populations of Hammerhead sharks, rays, dolphins and other large marine species. The extremely wet climate and oceanic character give Cocos an ecological character that is not shared with either the Galapagos Archipelago or any of the other islands (e.g., Malpelo or Coiba) in this region of the world.

Cocos Island was declared a Costa Rican National Park by means of Executive Decree in 1978. Cocos Island National Park was designated a World Heritage Site by UNESCO in 1997. In 2002, the World Heritage Site designation was extended to include an expanded marine zone of 1,997 km². In addition, it is included in the list of "Wetlands of International Importance".

Cocos Island was short-listed as a candidate to be one of the New7Wonders of Nature by the New Seven Wonders of the World Foundation. As of June 2009 it is ranking second in the islands category.
The only persons allowed to live on Cocos Island are Costa Rican Park Rangers, who have established two encampments, including one at Chatham Bay. Tourists and ship crew members are allowed ashore only with permission of island rangers, and are not permitted to camp, stay overnight or collect any flora, fauna or minerals from the island.

This island is popular in pirate lore as well. It is said that over 300 expeditions have gone in search of treasure such as the hoard of Benito Bonito, the Treasure of Lima, and many others. Some incidents of small caches have been discovered, leading many to believe the stories of vast pirate treasures to be valid.