It is not certain who from Western civilization discovered Hawaii.

An excerpt from the article 16 facts about Hawaii

The Spanish claim that this was done by the captain of their fleet, Ruy López de Villalobos, in 1542. The island was named "Isla de Mesa, de los Monjes y Desgraciada". What is certain, however, is that the British explorer James Cook arrived in Hawaii in 1778. The British brought weapons with them to the islands, which contributed to the creation of the Kingdom of Hawaii.