The island of Maui is the second-largest of the Hawaiian Islands at 727.2 square miles 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, which include Molokaʻi, Lānaʻi, and unpopulated Kahoʻolawe. In 2010, Maui had a population of 144,444, third-highest of the Hawaiian Islands, behind that of Oʻahu and Hawaiʻi Island. Kahului is the largest census-designated place 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 Kīhei (including Wailea and Makena in the Kihei Town CDP, the island’s second-most-populated CDP), Lāhainā (including Kāʻanapali and Kapalua in the Lāhainā Town CDP), Makawao, Pukalani, Pāʻia, Kula, Haʻikū, and Hāna.
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.Looking into the Haleakalā craterVolcanic rocks protrude on a Maui beachThe 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). Puʻu Kukui is the highest of the peaks at 5,788 feet (1,764 m). The larger, younger volcano to the east, Haleakalā, rises to more than 10,000 feet (3,000 m) above sea level, and measures 5 miles (8.0 km) from seafloor to summit.
The eastern flanks of both volcanoes are cut by deeply incised valleys and steep-sided ravines that run downslope to the rocky, windswept shoreline. The valley-like Isthmus of Maui that separates the two volcanic masses was formed by sandy erosional deposits.Maui’s last eruption (originating in Haleakalā’s Southwest Rift Zone) occurred around 1790; two of the resulting lava flows are located (1) at Cape Kīnaʻu between ʻĀhihi Bay and La Perouse Bay on the southwest shore of East Maui, and (2) at Makaluapuna Point on Honokahua Bay on the northwest shore of West Maui. Considered to be dormant by volcanologists, Haleakalā is certainly capable of further eruptions.The climate of the Hawaiian Islands is characterized by a two-season year, tropical and uniform temperatures everywhere (except at high elevations), marked geographic differences in rainfall, high relative humidity, extensive cloud formations (except on the driest coasts and at high elevations), and dominant trade-wind flow (especially at elevations below a few thousand feet). Maui itself has a wide range of climatic conditions and weather patterns that are influenced by several different factors in the physical environment:Half of Maui is situated within 5 miles (8.0 km) of the island’s coastline.