Darwin spent almost five years on board a Royal Navy exploring ship, the HMS "Beagle". He was the guest naturalist, which meant that he was responsible for making collections and notes about the animals, plants, and the geology of the countries they visited. The ship's crew made charts of all the coastal areas, which could be used by the navy wherever it went in the world. At the time, Britain had by far the largest navy in the world, and an empire which was global.