HMS Beagle’s voyage inspired Darwin’s theory of coral reef and atoll formation. Darwin sailed as the expedition’s naturalist on the ship’s second voyage, commanded by Captain Robert FitzRoy from 1831 to 1836.
During the expedition, Darwin studied the geology of rising land, volcanic islands, and coral formations. He began to reason that reefs could keep growing upward in shallow water as an island and the surrounding ocean floor slowly subsided. This offered an explanation for the sequence from fringing reef to barrier reef to atoll.
The Beagle’s survey of the Keeling Islands was especially important. Darwin observed a coral ring enclosing a lagoon and used the island’s structure, reef distribution, and soundings to test his ideas. He had already developed much of the theory before seeing many Pacific atolls directly.
HMS Bounty, HMS Endeavour, and HMS Challenger were also famous exploration vessels, but they were not the ship whose voyage provided Darwin’s defining observations for this theory. The ship’s full name is usually written HMS Beagle.