The volcanic vents that formed Hanauma Crater opened on the sea floor. Upwelling magma vaporized the ocean water and steam explosions atomized the magma into fine ash. 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. This image, acquired by the Ikonos satellite on November 7, , shows Hanauma Bay and the surrounding crater. Shallow reefs along the shorline appear to almost break the surface of the water. The Bay is now a flooded crater surrounded by several cratered cones. It is likely that its oceanside rim was low to begin with because the ash was carried away by tidal currents and trade winds.
The present opening to the sea is probably the result of wave erosion. The violent explosions that created Hanauma Bay and this southeastern part of the island blasted up through a previously established coral reef. As you walk down to or around the Bay, you will see fragments of white coral limestone and dark basalt rock imbedded in the walls of tuff.
In some areas you may find large pieces of rock and coral that were ejected by eruptions. These large fragments fell into the unconsolidated ash and compressed the layers of ash below them, creating bomb sags in the tuff. If you look carefully, you can sometimes see the shock pattern that the rock left in the tuff.
Small crystals of green olivine can also be seen in the crater walls and the sands of the bay, particularly around the "Toilet Bowl" section of the Bay. Four public telephones and 9 business phones are located in the beach area. Hanauma Bay Preserve contains four restroom buildings. Effluent from the plant is discharged through an offshore outfall extending 3, feet off Sandy Beach.
This secondary sewage treatment is released in 35 feet of water. Economic Value and Social Benefits:. The ordinance went into effect July 1, The ordinance went into effect on April 25, Parking fees are also charged to tour buses. Graph showing the revenue accrued by Hanauma Bay. Marine Life Conservation District. Established to conserve and replenish marine resources, MLCDs provide fish and other marine life with a protected area in which they can grow and reproduce.
While state laws restrict the taking of all marine life within the Hanauma Bay MLCD, snorkeling, diving, underwater photography, and other similar passive activities are allowed. Management Concerns:. Hanauma Bay has experienced very high levels of human use over the past 35 years. Primary impacts have been through fish feeding, trampling of corals, and structural change of the reef through the installation of a submarine cable.
Areas of management concern include the impact of visitors on the reef and biota, the impact of fish feeding , and the "carrying capacity" in visitor numbers of the site. Number of visitors at Hanauma Bay.
The figure above is based on headcounts at approximately two hour intervals taken by water safety officers over an eight hour work day. Data is from June 1 to May 31 for each year. These data may be somewhat unreliable as the counts are not exact and are taken by different water safety officers. Fish Feeding in Hanauma Bay. Information summarized from: Wright, Walter.
Delay in enforcing feeding ban at Hanauma allows more research. Honolulu Advertiser. Thursday, April 29, Page B1. Brock can measure the "before" and "after: effects as part of his study. Fish populations will shift away from nenue rudder fish and pualu surgeonfish that thrive on artificial food supply and currently dominate the inshore reef. The nenue and pualu will be replaced by more colorful weke goatfish , parrotfish, butterflyfish and damselfish.
There may be a decline in numbers of fishes, but reduction in larger fishes may be made up by increases in number of smaller fishes.
Because the change will be gradual, no mass die-offs of any kind are expected. The numbers of eels, which feed on other fish, may also gradually decline. Historical and Cultural Importance:. The Place Name Hanauma. Hanauma pronounced "ha now ma" is a Hawaiian word that can have several meanings. Originally, the Hawaiian language was not a written language. It was passed down orally through song, dance, stories and legends from one generation to the next.
This oral transmission resulted in some changes and loss of place names. Place names frequently described a salient landmark or feature or may describe an important historical event. In place names, hana refers to a bay or valley. Uma can have multiple meanings:. Thus, three suggested meanings for Hanauma Bay are: curved bay, hand-wrestling bay, canoe stern bay Name origin dictionary of Hawaiian localities-Pukui.
Historical Background:. King Kamehameha V used the bay often for fishing. Historic Events:. It is governed by State statutes, Regulation It states that it is unlawful to fish, possess fishing gear, remove any marine organisms or contaminate the waters within the conservation district.
This law is enforced by the Department of Land and Natural Resources. Prior to , most types of fishing was allowed in the bay. It was a popular fishing and camp grounds for people from Honolulu. Ernst Reese had proposed that the bay be set aside as a natural, living museum. Many fishermen protested this idea for fear of setting a precedent to close other traditional fishing grounds. Many legends were told of Hanauma Bay. Paved roads arrived in along with modest bathroom facilities and a guide rail for the steep passageway down to the base of the crater wall.
After World War II, construction of the area increased with new restrooms and showers. Hanauma Bay quickly became a hot tourist spot and suffered from overuse throughout the next few decades.
In the s, measures were taken to start preserving the area and reducing the impact of visitors.
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