Map - Oahu (O‘ahu)

Oahu (Hawaiian: Oʻahu ), also known as "The Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over two-thirds of the population of the U.S. state of Hawaii. The island of O’ahu and the Northwestern Hawaiian Islands constitute the City and County of Honolulu. The state capital, Honolulu, is on Oʻahu's southeast coast. Oʻahu had a population of 1,016,508 according to the 2020 U.S. Census, up from 953,207 in 2010 (approximately 70% of the total 1,455,271 population of the State of Hawaii, with approximately 81% of those living in or near the Honolulu urban area).

The Island of Oahu in Hawaii is often nicknamed (or translated as) "The Gathering Place". It appears that Oahu grew into this nickname; it is now the most populous Hawaiian Island, but in ancient times was not populous and was outranked by the status of other islands. The translation of "gathering place" was suggested as recently as 1922 by Hawaiian Almanac author Thomas Thrum. It has been speculated that Thrum ignored or misplaced the okina because the Hawaiian phrase "o ahu" could be translated as "gathering of objects" (o is a subject marker and ahu means "to gather"). The term Oʻahu has no confirmed meaning in Hawaiian, other than that of the place itself.

The city of Honolulu—largest city, the state capital, and main deepwater marine port for the State of Hawaiʻi—is here. As a jurisdictional unit, the entire island of Oʻahu is in Honolulu County, although as a place name, Honolulu occupies only part of the southeastern end of the island.

Well-known features of Oʻahu include Waikiki, Pearl Harbor, Diamond Head, Hanauma, Kāneʻohe Bay, Kailua Bay, North Shore, and the resort destination Ko Olina.

While the island is designated the City and County of Honolulu, excluding the minor Northwestern Hawaiian Islands, residents identify settlements using town names (generally those of the census-designated places), and consider the island divided into various areas that may overlap. The most commonly accepted areas are the "City", "Town" or "Town side", which is the urbanized area from Halawa to the area below Diamond Head (residents of the island north of the Koʻolau Mountains consider the Town Side to be the entire southern half), "West Oʻahu", which goes from Pearl Harbor to Kapolei, ʻEwa and may include the Waiʻanae and Mākaha areas; the "North Shore" (northwestern coast); the "Windward Side" (northeastern coast from Kahuku to Kāneʻohe); the "East Side" or "East Coast" (the eastern portion of the island, from Kāneʻohe on the northeast, around the tip of the island to include much of the area east of Diamond Head); and "The Valley" or "Central Oʻahu", which runs northwest from Pearl Harbor toward Haleʻiwa. These terms are somewhat flexible, depending on the area in which the user lives, and are used in a general way, but residents of each area identify strongly with their part of the island, especially those outside of widely known towns. For instance, if asked where they live, a local would usually reply "Windward Side" rather than "Kailua".