Ten Interesting Facts About Hanauma Bay

You have probably seen Hanauma Bay’s crystal clear waters as it is one of the most photographed places on Oahu. Hundreds of years ago Hawaiians gathered here in canoes to wait for calmer winds so they could paddle out to sea to fish or travel to distant islands.

1. Royalty used to fish here.

Originally the property of King Kamehameha, Hanuama Bay was a favorite fishing camp of Hawaiian royalty.  In 1795 Kamehameha’s wife, Queen Ka’ahumanu, arrived by canoe where hula dancers and hand-wrestlers entertained her for an entire month.

2. Hanauma Bay is protected.

Today, Hanauma Bay is a protected marine life conservation area managed by the state to protect the fragile reef and ecosystem.

3. Artifacts were found in a cliff-side cave.

In 1952, the University of Hawaii excavated a 210 sq ft cave in the cliff wall on the far side of the bay where they found animal bones, cooking stones, fishhooks and other tools dating back several hundred years.

Fishing Artifacts

4. Hanauma Bay used to be covered by water.

One hundred thousand years ago, the entire area including the surrounding hills was underwater.  The ocean waves pounded at the base of the Ko’olaus and a coral reef grew in the area.

5. “Hanauma” means “curved bay”.

It is a natural pool in a volcanic crater that formed about forty thousand years ago.  After years of waves pounding on the outer rim of the crater, the walls finally broke away and the ocean filled the crater forming the curved bay.

Hanauma Bay Opening

6. Protections were placed at Hanauma Bay to protect Oahu from invasion in WWII.

In 1941, shortly after the bombing of Pearl Harbor, the US Army strung barbed wire along the beach and stationed soldiers there to repel a possible Japanese invasion that might enter through the bay.

Soldier at Hanauma Bay

7. In 1956 the Hawaiian Telephone Company blasted a two hundred foot wide channel through the reef to lay a Trans Pacific undersea telephone cable.

A resulting oil slick covered the bay and in a few days, the majority of the coral reef was dead.  Eventually, a reef of large boulders was installed, sheltering the original swimming area from incoming waves, making it more habitable for marine life. Rubble was buried under the beach and covered with 4000 cubic feet of white sand from O`ahu’s North shore to repair the erosion.

Hanauma Beach

8. This is a variety of marine life at Hanauma Bay.

  • The Hawaii state fish: Humuhumunukunukuapua’a or Reef Triggerfish
  • The Moray eel: Snakelike with thick, scale-less skin, and up to five feet long.  They like rocky areas, holes under rocks and coral crevices where they wait for prey.
  • Sea urchins: Reside in the upper tide pools of Hanauma Bay, making their own holes with their sturdy spines. These spines are not toxic but sharp enough to be painful if stepped on.
  • The Box Jellyfish: Named for its cube shaped appearance, has no true head, heart, brain or skeleton, and is 95% water.
  • White-tipped reef sharks: Reside and rest on the sandy bottom beneath a ledge just inside the reef. They grow to five feet long and hunt octopus, crustaceans and fish.

Mural at Hanauma Bay Entrance

9. The Bay has a living coral forest that grows and feeds the marine life.

The coral formations and creatures that live there provide some of the most beautiful underwater landscapes on the planet.

Hanauma Bay Water and Coral

10. Quite a few movies were filmed here.

Movies filmed here include Donovan’s Reef with John Wayne and Lee Marvin, Blue Hawaii and Paradise Hawaiian Style with Elvis Presley, and Tora!Tora!Tora with Joseph Cotton and E.G. Marshall. Commercial filming was halted in 1990 to support the Bay’s educational focus. Limited exceptions have been made for organizations like the National Geographic Society who support Hanauma Bay’s conservation message.