The aptly named O'ahu (Hawaiian for "the gathering place") is the third largest of the Hawaiian islands and most populous island in the state. Total land area is 608 sq. miles. The city of Honolulu — largest city, capital, and main deepwater marine port for the State of Hawaii — is located here. As a jurisdictional unit, the entire island is in the City & County of Honolulu, although as a place name Honolulu occupies only a portion of the sothwest coast of the island. The island extends from Ka'ena on the west to Makapu'u on the east. Other well-known features found on O'ahu are Waikīkī, Pearl Harbor, Diamond Head, Hanauma Bay, Kāne'ohe Bay, and the North Shore.
Hanauma Bay on O'ahu (Another image is )
Kamehameha I first established O'ahu as his capital when he became the first of the Hawaiian ali'i (royalty) to rule all the islands. 'Iolani Palace, built later on by others of the royal family, still remains as evidence of the only monarchy on American soil.
O'ahu was apparently the first of the Hawaiian Islands sighted by the crew of HMS Resolution on 18 January 1778 during Capt. 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. O'ahu was not actually visited by Europeans until 28 February 1779 when Captain Clerke aboard HMS Resolution stepped ashore at Waimea Bay. Clerke had taken command of the ship after Capt. Cook was killed at Kealakekua Bay on February 14, and was leaving the islands for the North Pacific.
Today, O'ahu has become a tourism and shopping haven as over 5 million visitors (mainly from the American mainland and Japan) flock there every year to enjoy the quintessential island holiday experience that Hawaii personifies.
O'ahu has been featured in hundreds of movies and TV shows, including Magnum P.I, Hawaii Five-O and Jake and the Fatman to name but a few.