Nickname: The Gathering Place
|Location||21°28′23″N157°59′12″W / 21.4730°N 157.9868°W|
|Area||596.7 sq mi (1,545 km2)|
|Area rank||3rd largest Hawaiian Island|
|Highest elevation||4,025 ft (1226.8 m)|
|Pop. density||1,704/sq mi (657.9/km2)|
Oahu ( /oʊˈɑːhuː/ ) (Hawaiian: Oʻahu (pronounced [oˈʔɐhu] )), 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 995,638  according to 2022 U.S. census estimates, 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 Oʻahu in Hawaii is often nicknamed (or translated as) "The Gathering Place". It appears that Oʻahu 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[ by whom? ] that Thrum ignored or misplaced the ʻokina because the Hawaiian phrase "ʻo ahu" could be translated as "gathering of objects" (ʻo 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—the state's largest city, capital, and main deepwater marine port—is here. As a jurisdictional unit, all of Oʻahu is in Honolulu County, although Honolulu occupies only part of its southeastern end.
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.[ citation needed ] 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".[ citation needed ]
The island has been inhabited since at least the 3rd century A.D.  The 304-year-old Kingdom of Oʻahu was once ruled by the most ancient aliʻi in all of the Hawaiian Islands. The first great king of Oʻahu was Maʻilikūkahi, the lawmaker, who was followed by many generations of monarchs. Kualiʻi was the first of the warlike kings and was succeeded by his sons. In 1773, the throne fell upon Kahahana, the son of Elani of Ewa. In 1783, Kahekili II, King of Maui, conquered Oʻahu, deposed the reigning family, and made his son, Kalanikūpule, king of O'ahu, turning O'ahu into a puppet state. Kamehameha the Great conquered Kalanikūpule's forces in the Battle of Nuʻuanu. Kamehameha founded the Kingdom of Hawaiʻi with the conquest of Oʻahu in 1795. Hawaiʻi was not unified until the islands of Kauaʻi and Niʻihau surrendered under King Kaumualiʻi in 1810. Kamehameha III moved his capital from Lāhainā, Maui to Honolulu, Oʻahu in 1845. ʻIolani Palace, built later by other members of the royal family, still stands, and is the only royal palace on American soil.
Oʻahu was apparently the first of the Hawaiian Islands sighted by the crew of HMS Resolution on January 19, 1778, during Captain James Cook's third Pacific expedition. Escorted by HMS Discovery, the expedition was surprised to find high islands this far north in the central Pacific. Oʻahu was not actually visited by Europeans until February 28, 1779, when Captain Charles Clerke aboard HMS Resolution stepped ashore at Waimea Bay. Clerke took command of the ship after James Cook was killed at Kealakekua Bay (island of Hawaiʻi) on February 14, and was leaving the islands for the North Pacific. With the discovery of the Hawaiian Islands came the introduction of disease, mosquitoes, and aggressive foreign animals. Although indirect, simple exposure to these foreign species caused permanent damage to the Native Hawaiian people and environment.
The Imperial Japanese Navy's attack on Pearl Harbor, Oʻahu on the morning of December 7, 1941, brought the United States into World War II. The surprise attack was aimed at destroying the American will to fight and making them sue for peace immediately by attacking the Pacific Fleet of the United States Navy and its defending Army Air Forces and Marine Air Forces. The attack damaged or destroyed 12 American warships, destroyed 188 aircraft, and resulted in the deaths of 2,335 American servicemen and 68 civilians (of those, 1,177 were the result of the destruction of the USS Arizona alone).
Today, Oʻahu has become a tourism and shopping haven. Over five million visitors (mainly from the contiguous United States and Japan) flock there every year.
Oʻahu is also known for having the longest rain shower in history, which lasted 200 consecutive days. Kāneʻohe Ranch reported 247 straight days of rain from August 27, 1993, to April 30, 1994. The average temperature in Oʻahu is around 70–85 °F (21–29 °C). The island is the warmest from June through October. The winter is cooler, but still warm, with an average temperature of 68–78 °F (20–26 °C).
Oʻahu is 44 miles (71 km) long and 30 miles (48 km) across. Its shoreline is 227 miles (365 km) long. Including small associated islands such as Ford Island plus those in Kāneʻohe Bay and off the eastern (windward) coast, its area is 596.7 square miles (1,545.4 km2), making it the 20th-largest island in the United States.  The windward side is known for some of the world's most beautiful beaches. Lanikai Beach on the windward coast has been consistently ranked among the world's best beaches.  The island is composed of two separate shield volcanoes: the Waiʻanae and Koʻolau Ranges, with a broad valley or saddle (the central Oʻahu Plain) between them. The highest point is Kaʻala in the Waiʻanae Range, rising to 4,003 feet (1,220 m) above sea level. 
Being roughly diamond-shaped, surrounded by ocean, and divided by mountain ranges, directions on Oʻahu are not generally described with compass directions. Locals instead use directions with Honolulu as the central point. To go ʻewa means toward the western tip of the island, "Diamond Head" is toward the eastern tip, mauka is inland (toward the central Koʻolau Mountain range, north of Honolulu) and makai toward the sea. When these directions became common, Diamond Head was the eastern edge of the primary populated area. Today, with a much larger populace and extensive development, the mountain is often not actually to the east when directions are given, and is not to be used as a literal point of reference—to go "Diamond Head" is to go to the east from anywhere on the island.
Beginning with a contract with the US Navy in 2001, Ocean Power Technologies began ocean-testing Azura, its wave power generation system at the Marine Corps Base Hawaii (MCBH) at Kāneʻohe Bay. The Oʻahu system was launched under the company's program with the US Navy for ocean testing and demonstration of such systems, including connection to the Oʻahu grid.  The prototype can produce 20 kW, a system with 500 kW to 1 MW is planned to be installed at end of 2017. 
Oʻahu has 343 MW of rooftop solar power,  and potential for 92 MW of wind power.  
Honolulu is the capital and most populous city of the U.S. state of Hawaii, which is in the Pacific Ocean. It is the unincorporated county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the island of Oʻahu, and is the westernmost and southernmost major U.S. city. Honolulu is Hawaii's main gateway to the world. It is also a major hub for business, finance, hospitality, and military defense in both the state and Oceania. The city is characterized by a mix of various Asian, Western, and Pacific cultures, reflected in its diverse demography, cuisine, and traditions.
Interstate H-3 (H-3) is an Interstate Highway located entirely within the US state of Hawaii on the island of Oʻahu. H-3 is also known as the John A. Burns Freeway, after the second governor of Hawaii. It crosses the Koʻolau Range along several viaducts and through the 5,165-foot-long (1,574 m) Tetsuo Harano Tunnels as well as the much smaller Hospital Rock Tunnels.
Kailua is a census-designated place (CDP) in Honolulu County, Hawaii, United States. It lies in the Koʻolaupoko District of the island of Oʻahu on the windward coast at Kailua Bay. It is in the judicial district and the ahupua'a named Ko'olaupoko. It is 12 miles (19 km) northeast of Honolulu – over Nu‘uanu Pali.
Kāneʻohe is a census-designated place (CDP) included in the City and County of Honolulu and in Hawaiʻi state District of Koʻolaupoko on the island of Oʻahu. In the Hawaiian language, kāne ʻohe means "bamboo man". According to an ancient Hawaiian story, a local woman compared her husband's cruelty to the sharp edge of cutting bamboo; thus the place was named Kāneʻohe or "bamboo man".
Marine Corps Base Hawaii (MCBH), formerly Marine Corps Air Station Kaneohe Bay and originally Naval Air Station Kaneohe Bay, is a U.S. Marine Corps facility and air station located on the Mokapu Peninsula of windward O'ahu in the City & County of Honolulu. Marine Corps Base Hawaii is home to Marines, Sailors, their family members, and civilian employees. The United States Marine Corps operates a 7,800-foot (2,400 m) runway at the base.
Mākaha is a census-designated place (CDP) in Honolulu County, Hawaiʻi, United States. It is a town located along the Pacific coast, west of the Mākaha Valley, and at the foot of Mt. Ka'ala in the Wai’anae Mountain Range. It is the last of the leeward towns on O'ahu. North of Mākaha there is no development, i.e. no towns, no gas stations, or restaurants. The population of Mākaha was 8,278 at the 2010 census. It is located 35 miles northwest of Honolulu, but is a part of Honolulu County.
Waimea Bay is located in Haleiwa on the North Shore of O'ahu in the Hawaiian Islands at the mouth of the Waimea River. Waimea Valley extends to the east of Waimea Bay. Waimea means "reddish water" in Hawaiian.
Waikāne or Waikane, also known as North Koʻolaupoko, is an area and census-designated place in the County of Honolulu, Hawaii, United States, on the island of Oʻahu. It had a population of 778 at the 2010 census. In Hawaiian, koʻolau poko means "short windward", referring to the fact that this is the shorter of the two windward districts on the island. Koʻolaupoko extends from Makapuʻu Point on the southeast to Kaʻōʻio Point on the north. Included within the district, south of North Koʻolaupoko, are the largest windward towns of Kāneʻohe, Kailua, and Waimānalo.
Diamond Head is a volcanic tuff cone on the Hawaiian island of Oʻahu and known to Hawaiians as Lēʻahi. The Hawaiian name is most likely derived from lae plus ʻahi (tuna) because the shape of the ridgeline resembles the shape of a tuna's dorsal fin. Its English name was given by British sailors in the 19th century, who named it for the calcite crystals on the adjacent beach.
The following is an alphabetical list of articles related to the U.S. state of Hawaii:
The Hawaii State Public Library System (HSPLS) is the only statewide public library system in the United States.
Hanauma is a marine embayment formed within a tuff ring and located along the southeast coast of the Island of Oʻahu in the Hawaii Kai neighborhood of East Honolulu, in the Hawaiian Islands.
Koʻolau Range is a name given to the dormant fragmented remnant of the eastern or windward shield volcano of the Hawaiian island of Oʻahu. It was designated a National Natural Landmark in 1972.
Route 63 is a state highway on the island of Oʻahu in Honolulu County, Hawaiʻi, United States, that is one of three main highways passing through the Koʻolau mountain.
Nuʻuanu Pali is a section of the windward cliff of the Koʻolau mountain located at the head of Nuʻuanu Valley on the island of Oʻahu. It has a panoramic view of the windward (northeast) coast of Oʻahu. The Pali Highway connecting Kailua/Kāneʻohe with downtown Honolulu runs through the Nuʻuanu Pali Tunnels bored into the cliffside.
Honolulu County is a consolidated city-county in the U.S. state of Hawaii. The city-county includes both the city of Honolulu and the rest of the island of Oʻahu, as well as several minor outlying islands, including all of the Northwestern Hawaiian Islands except Midway Atoll.
The transportation system of Hawaii is a cooperation of complex systems of infrastructure.
The Hawaii Pacific Baptist Convention (HPBC) is a group of churches affiliated with the Southern Baptist Convention located in the U.S. state of Hawaii and other pacific regions. Headquartered in Honolulu, it is made up of 138 churches on 11 islands in 6 Baptist associations.