Cocos Island Nation­al Park, locat­ed 550 km off the Pacif­ic coast of Cos­ta Rica, is the only island in the trop­i­cal east­ern Pacif­ic with a trop­i­cal rain­for­est. Its posi­tion as the first point of con­tact with the north­ern equa­to­r­i­al counter-cur­rent, and the myr­i­ad inter­ac­tions between the island and the sur­round­ing marine ecosys­tem, make the area an ide­al lab­o­ra­to­ry for the study of bio­log­i­cal process­es. The under­wa­ter world of the nation­al park has become famous due to the attrac­tion it holds for divers, who rate it as one of the best places in the world to view large pelag­ic species such as sharks, rays, tuna and dol­phins.