Hanauma Bay History
Table of Contents
Mahalo for your interest in learning more about the history of Hanauma Bay, from its modern day recognition and use to its geological roots millions of years ago! Scrolling through this page is akin to going back in time to see how this unique environmental marvel has progressed over time.
Modern Milestones
50th Anniversary as State’s First Marine Life Conservation District – Oct. 2017
In October 1967, the State designated the 100-acre Hanauma Bay as Hawai‘i’s first Marine Life Conservation District (MLCD). This designation made it illegal to fish or remove any marine life or other marine resources from the bay. It provided the mechanism for DLNR to have an active and formal role in the management and protection of the bay’s ocean waters. DAR biologists have been surveying fish populations in the bay since 1969. This has helped ensure the bay continues as having the largest biomass of reef fish anywhere around O‘ahu.
In 2023, approximately 400,000 visits to the bay were recorded. Visitors from all over the world came the bay to take in its vast marine and coral life. They snorkel, dive, spend time tanning on the beach, and otherwise enjoy the bay’s natural beauty. Before going into the water, they are educated about the living reef environment and safety practices to help ensure their continued enjoyment of the bay. The State, through the DLNR Division of Aquatic Resources (DAR) and the Office of Conservation and Coastal Lands (OCCL); the City and County of Honolulu, through the Department of Parks and Recreation (DPR), and Ocean Safety and Lifeguard Services; the University of Hawai‘i Sea Grant Program, and the non-profit Friends of Hanauma Bay continue work together to protect the bay’s unique underwater resources and ensure the health of fish, corals, marine mammals, and visitors of the bay.
Marine Education Center wind three design awards in a month – May 2003
The American Institute of Architects Honolulu Chapter (AIA Honolulu) and the Hawaii Chapter of the National Association of Industrial and Office Properties (NAIOP) recognized the Hanauma Bay Marine Education Center with awards for excellence. These are the second and third prestigious design awards the popular marine attraction received in summer 2003. Previously, the Hawai‘i Visitors and Convention Bureau also honored the City project with its Kahili Award for architecture.
In granting the Marine Education Center the prestigious Award of Merit, AIA Honolulu judges noted its “adventurous, people-oriented” design that preserves the scenic beauty of the crater rim by blending naturally with the environ
ment. NAIOP recognized the Education Center with its Kûkulu Hale Award for New Public Projects, taking special note of the designers’ efforts to house the facility’s educational functions by making them largely indiscernible from public approach and the floor of the bay, thus preserving the natural integrity of the surrounding environment.
The Hanauma Bay Marine Education Center was opened to the public in August 2002, following extensive improvements to the grounds and facilities at Nature Preserve. The 8,100 square foot facility features a theater, an education alcove, gift shop and food concession at the upper level of the Bay. The facility
takes the art of low profile to a new level–underground. The cave-like environment preserves the scenic beauty of the crater rim by remaining largely imperceptible from the public approach and the floor of the bay; man-made rock walls were formed with molds cast from the existing cliff face.
Modern Timeline
Geology
The Hawaiian Islands archipelago is the most isolated island chain in the world. It extends from the Island of Hawai’i to Kure Atoll in the northwest, a distance of over 1,500 miles. The Hawai’i Island is the youngest.
The Islands are a group of volcanos that have risen up over a “hot spot” of molten rock that wells up from deep in the earth’s interior. As the ocean floor slowly moves over this spot, islands are born. They are then carried towards the northwest as they erode and slowly sink below the waves.
O’ahu first rose above the sea nearly 4 million years ago as the Wai’anae volcano. The younger Ko’olau volcano, on the east side of O’ahu, is about 2.7 million years old. It is larger than the Wai’anae, and makes up most of the island. Nearly 2 million years ago, the eastern flank of the Ko’olau volcano collapsed and slid into the sea, leaving the steep mountain range that we see today on the windward side.
A quiet period followed the eruptions that formed the Ko’olaus until energetic rejuvenation-stage volcanism started to occur about a million years ago. This “Honolulu Volcanic Series” created many well-known landmarks including Diamond Head, Punchbowl, and Hanauma Bay.
The present site of Hanauma Bay was underwater 100,000 years ago. The ocean lapped at the base of the Ko’olaus and a coral reef grew in the area. Text and below photos courtesy of John Hoover and Richard Duggan
The youngest craters and cones of the Honolulu Series are part of Koko Head Regional Park, which lies along the Koko rift zone. This region has had the most recent volcanic activity on O’ahu, and it may not be over yet.
The lava flows that created the Hanauma Bay region started about 40,000 years ago. Koko Crater, the tallest and best preserved cinder and ash cone, is possibly one of the latest volcanic vents. Radiocarbon dates of volcanic rock and reef indicate that the last volcanic event in this area occurred just 7,000 years ago.
The youngest craters and cones of the Honolulu Series are part of Koko Head Regional Park, which lies along the Koko rift zone. This region has had the most recent volcanic activity on O’ahu, and it may not be over yet.
The lava flows that created the Hanauma Bay region started about 40,000 years ago. Koko Crater, the tallest and best preserved cinder and ash cone, is possibly one of the latest volcanic vents. Radiocarbon dates of volcanic rock and reef indicate that the last volcanic event in this area occurred just 7,000 years ago.
About 32,000 years ago Hanauma Bay was created in a violent series of explosions. Hydromagmatic blasts happened when a volcanic vent opened underwater. The erupting magma blew up in a bursts of steam, hot gases, rock, coral, and fine ash that blanketed the area. The ash chemically cemented together over time into the firm rock called tuff .
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. Olivine is a mineral that is found in areas of recent volcanic activity, like that which happened here.
Sea cliffs formed as the crater walls of Hanauma Bay eroded. Wave action, weathering and daily heating and drying of the walls undercut the tuff. This caused large areas to fall into the sea or on the bench (ledge) that developed below the cliffs.
Although the bench was exposed to wave action, water prevented the bench from drying out and weakening. The ledge formed due to the erosion of the cliffs by wind and salt, rather than the bench being degraded by waves. Text and photos courtesy of John Hoover and Richard Duggan