The island of Maui (ˈmaʊi; Hawaiian: ˈmɐwwi) is the second-largest island of the state of Hawaii at 727.2 square miles (1,883 km2), and the 17th-largest island in the United States. Maui is the largest of Maui County's four islands, which include Molokai, Lānai, and unpopulated Kahoolawe. In 2020, Maui had a population of 168,307, the third-highest of the Hawaiian Islands, behind Oahu and Hawaii Island. Kahului is the largest census-designated place (CDP) on the island, with a population of 28,219 , and the island's commercial and financial hub. Wailuku is the seat of Maui County and is the third-largest CDP . Other significant places include Kīhei (including Wailea and Makena in the Kihei Town CDP, the island's second-most-populated CDP), Lāhainā (including Kāanapali and Kapalua in the Lāhainā Town CDP), Makawao, Pukalani, Pāia, Kula, Haikū, and Hāna.
Native Hawaiian tradition gives the origin of the island's name in the legend of Hawaiiloa, the navigator credited with discovering the Hawaiian Islands. According to it, Hawaiiloa named the island after his son, who in turn was named for the demigod Māui. Maui's previous name was Ihikapalaumaewa. The Island of Maui is also called the "Valley Isle" for the large isthmus separating its northwestern and southeastern volcanic masses.
Maui's diverse landscapes are the result of a unique combination of geology, topography, and climate. Each volcanic cone in the chain of the Hawaiian Islands is built of [basalt], a dark, iron-rich/silica-poor rock, which poured out of thousands of vents as highly fluid lava over millions of years. Several of the volcanoes were close enough to each other that lava flows on their flanks overlapped one another, merging into a single island. Maui is such a "volcanic doublet," formed from two shield volcanoes that overlapped one another to form an isthmus between them.
The older, western volcano has been eroded considerably and is cut by numerous drainages, forming the peaks of the West Maui Mountains (in Hawaiian, Mauna Kahalawai).