The island of Mauiis the second-largest of the Hawaiian Islands at 727.2 square miles (1,883 km²) and is the 17th largest island in the United States. Maui is part of the State of Hawaii and is the largest of Maui County's four islands, bigger than Molokai, Lanai, and unpopulated Kahoolawe.
In 2010, Maui had a population of 144,444, third-highest of the Hawaiian Islands, behind that of Oahu and Hawaii Island. Kahului is the largest census-designated place (CDP) on the island with a population of 26,337 as of 2010 and is the commercial and financial hub of the island.
Wailuku is the seat of Maui County and is the third-largest CDP as of 2010. Other significant places include Kihei (including Wailea and Makena in the Kihei Town CDP, which is the second-most-populated CDP in Maui); Lahaina (including Kaanapali and Kapalua in the Lahaina Town CDP); Makawao; Paia; Kula; Haiku; and Hana.
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 dark, iron-rich/quartz-poor rocks, which poured out of thousands of vents as highly fluid lava, over a period of 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 climate of the Hawaiian Islands is characterized by a two-season year, mild and uniform temperatures everywhere, marked geographic differences in rainfall, high relative humidity, extensive cloud formations, and dominant trade-wind flow.