Hanauma Bay is a marine embayment formed within a tuff ring and located along the southeast coast of the Island of Oʻahu. Hanauma Bay is one of the most popular tourist destinations on the Island and has suffered somewhat from overuse hosting over three million visitors per year. The Hanauma Crater was created about 32,000 years ago during the Honolulu volcanic series, the latest and final round of volcanic activity to occur on Oʻahu. Tens of thousands of years ago, a series of volcanic vents opened along the southeast shoreline of Oʻahu. Unlike the gentle lava flows currently building the island of Hawaiʻi, the late-stage eruptions on Oʻahu were most often short-lived violent explosions. The volcanic vents that formed Hanauma Crater opened on the sea floor. Upwelling magma vaporized the ocean water and steam explosions blew the magma into fine ash. The explosions built cones or rings of ash, which solidified into tuff. The eruptions shattered the sea floor—coral reef and basalt—and scattered pieces that are now embedded in the tuff. Wave erosion eventually cut through the low, southeast wall of the crater, forming the current bay. Throughout history, due to the lack of fresh water in the vicinity, the area was not inhabited, although archeologists have found fishing tools and other indications of human presence there. The bay was used as a recreational area by the Hawaiian nobility, including King Kamehameha and Queen Ka‘ahumanu, who fished, entertained visitors, and sponsored games there. It was also used as a layover and as a navigational lookout point, since the waters between Oahu and Molokai are at times difficult.Hanauma Bay was purchased from the Bernice Pauahi Bishop estate by the City and County of Honolulu, and subsequently opened for public use. It was initially a favorite fishing and picnic spot for residents who were willing to travel out to the bay. In the 1930s the road along Hanauma Bay's corner of Oahu was paved and a few other amenities provided that made it easier to visit the beach and reef. After the 1941 attack on Pearl Harbor, barbed wire was placed at the beach and a bunker was constructed for use by sentries. The Bay area reopened after the war and became even more visitor friendly after blasting in the reef for a transoceanic cable provided room for swimming. Hawaii-themed films and television shows, including Blue Hawaii, Paradise, Hawaiian Style, Tora! Tora! Tora!, Hawaii Five-O, and Magnum, P.I., shot footage at the bay.In 1967 it was set apart by the State division of Fish and Game as a Marine Protected Area, a term used generically to describe any marine area that had some or all of its resources protected. In Hanauma Bay's case everything became protected, from the fish to the reef, to the sand itself. A volunteer group set up a booth at the beach and began teaching visitors about conservation of the reef and fish who lived there. More changes in the 1970s by the City cleared more area in the reef for swimming, made an additional parking lot, and shipped in white sand from the North Shore, leaving Hanauma Bay increasingly more attractive to visitors.By the late 1980s the bay had become a major attraction on Oahu. Tourists were brought in by the busload and sometimes as many as 13,000 visitors descended on the beach in one day. Most were uneducated about the fragile marine ecosystem and, unwittingly, "these crowds stirred up sediment, disturbed and trampled the coral and algae, dropped trash, fed the fish and left a slick of suntan lotion on the bay's surface." Consequently, the beautiful multicolored coral reef closest to the beach died; only its blackened skeleton is visible today. By 1990 overuse of the beach and surrounding area was a real problem, with visitors walking on the reef, swarming the surrounding areas, parking on the grass and on the sides of the road. Commercial filming was banned during that year. Measures were taken to limit use and so visitor access was limited to the parking lot, and when it was full everyone after was turned away. In 1997, the city of Honolulu levied an entrance fee on non-residents of the state, leading to a class action lawsuit by a visitor, which was settled in favor of the city during 2004. Then in August 2002 the Marine Education Center was opened at the entrance to the bay, where still today new visitors must watch a short film and receive instruction about conservation of the Bay's resources. Upon watching the film, visitors are allowed to sign a form and skip any subsequent film if they should return within the following 365 days.Today Hanauma Bay sees an average of 3000 visitors a day, or around a million visitors a year. The majority are tourists. The bay is closed to tourists on Tuesdays in order to allow the fish a day of feeding without interruption by swimmers.