A visit from Charles Darwin
Charles Darwin developed his theory of atoll formation during a visit to the Cocos Keeling Islands in 1836, aboard the HMS Beagle. He spent some time exploring the southern atoll and also visited North Keeling (now Pulu Keeling National Park).
In his publication on coral reefs in 1842, he was the first to propose the theory of reef formation and evolution, building on his discovery of coralline fossils in inland areas and mountains earlier in his career, and on his visit to the Cocos Keeling Islands. His theory, which is still held as valid, explains the dynamics of the three principal categories of coral formation.