The National Park Service was right about the Hōlei Sea Arch

By Daniel Okafor · Reporting from New York ·

When the Hōlei Sea Arch fell into the Pacific, it confirmed warnings from the National Park Service that these coastal cliffs will not last.

When the Hōlei Sea Arch fell, it was not a tragedy. It was a scheduled event. Anyone who found the fall of this 90-foot structure of basalt surprising ignored the record. The National Park Service spent years documenting how the arch decayed. The ocean did not steal a landmark; it finished what it started 550 years ago.

A window of four days

The end came quickly. The arch stood on Wednesday, September 23. The arch was gone by Sunday night, September 27. CNN said the arch vanished while Volcanoes National Park was closed for Tropical Storm Nolo. The park reopened on Monday, September 28, to an empty space.

The park records the dates. The BBC said the arch was still projecting into the water on Wednesday. The National Park Service confirmed the fall on Friday. The structure did not fight the water; it gave way.

The cliffs failed slowly

The fall was the final step as the cliffs retreated. The U.S. Geological Survey said in 2014 that the arch would not last. They noted that the ocean crashes against the pillar every day. Each wave wears away the rock.

The land was already failing. Earthquakes during the 2018 Kīlauea eruption damaged cliffs around the arch. These shakes weakened the structure before it fell. New cracks appeared by January 2020. The National Park Service closed the original area for viewing that month.

The ocean continued its work. Tropical Storm Darby broke off a chunk of rock from the lower portion of the arch. The National Park Service said in 2021 that the formation would not last. They said the arch would eventually crumble into the sea.

Why does the sea destroy its creations?

The arch fell for the same reason as the Collapse of the Azure Window. The Azure Window was a natural arch that stood 28 metres tall on the island of Gozo, off Malta. It fell in stormy weather on 8 March 2017. Both structures fell because waves destroy the arches they carve.

The U.S. Geological Survey calls this differential erosion. Waves wear away soft rock faster than hard rock, which carved the Hōlei Sea Arch from ancient lava. The same waves that built the vault eventually hollowed the pillar.

The storms follow a known pattern that experts said matches El Niño years. A hotter planet makes these storms stronger. The damage mirrors Hurricane Katrina in 2005, which used severe surges to destroy coastal buildings after years of instability. The Pacific now follows a similar path.

The cost of curiosity

The Big Island constantly moves. Lava flows from Kīlauea threatened the Star of the Sea Painted Church in April 1990. Parishioners voted to move the building. They moved the church on May 4, 1990, just hours before lava covered Highway 137. The land does not stay still.

Some visitors refuse to accept this. Social media photos show people entering the closed area where the arch once stood. They walk on unstable edges of the cliffs to photograph a void. These visitors ignore the warnings of the National Park Service.

The park opened a safer area for viewing in March 2020. The area sits further from the edge of the cliff. The original overlook remains closed because the ground is not solid. The ocean is moving the coastline inland.

The fall of the Hōlei Sea Arch proves that the National Park Service was right to treat the coast as a hazard. The basalt cliffs are failing. The fallen arch no longer blocks the waves. Waves now strike the remaining shoreline directly. The park will likely close more areas along Chain of Craters Road as the land retreats. The immediate danger is the crowd of people who bypass barriers to photograph the site. These visitors will likely trigger a search and rescue operation when they fall into the freshly exposed voids. Nature does not promise that anything will last.

Sources

  1. The Guardian: Hawaii’s centuries-old sea arch collapses into Pacific after series of rough storms
  2. CNN: Hawaii’s famed Hōlei Sea Arch has collapsed
  3. National Park Service (.gov): Hōlei Sea Arch Collapses in Hawaiʻi Volcanoes National Park
  4. BBC: Hawaii's iconic 550-year-old Hōlei Sea Arch collapses
  5. Yonhap: 550년 된 하와이 용암아치 붕괴…허리케인 강타후 사라져