Captain James Cook gave the Hawaiian Islands the name Sandwich Islands in 1778. He arrived there on January 18 of that same year. They were named in a show of respect and admiration of one of his Admiralty trip sponsors, John Montagu, the 4th Earl of Sandwich. By the 1840s, though, the local name of Hawaii became more frequently used and eventually was officially adopted. Hawaii is mostly known for its eight large islands, but it actually is comprised of 137 islands, many of which are uninhabited. The Hawaiian Islands was created by volcanic activity in the underwater mountain range called the Hawaiian-Emperor seamount chain.