After 550 Years of Formation.. Collapse of One of the Most Famous Natural Landmarks in Hawaii

- A massive sea arch that has long been considered one of the most prominent natural landmarks on the rugged coast of Hawaii has collapsed into the Pacific Ocean after more than 500 years since its natural formation, according to local park management. The Hōlei Sea Arch stood about 27 meters high within Hawaii Volcanoes National Park on the southern coast of the Big Island, which is the largest and geologically youngest island in the Hawaiian archipelago.

The arch was formed about 550 years ago when ancient lava flows from one of the six volcanoes on the island reached the edges of the rocky cliffs, carving out this arched cavity, thus creating a natural wonder that attracted visitors to the site for many years, according to the U.S. National Park Service. Although the exact timing of the arch's collapse is unknown, the Hawaii Volcanoes National Park team indicated on social media on Thursday that the arch was still standing on Wednesday, September 23, when the park was temporarily closed during Tropical Storm Noul.

When the park reopened on Monday, September 28, the arch had disappeared. Hawaii Volcanoes National Park confirmed the news in posts on Facebook and Instagram, accompanied by before-and-after photos showing the significant change in the landscape: "Yes, it's true."

They added: "The Hōlei Sea Arch was a very special place for many of our visitors." However, this dramatic transformation of the remote coastal landscape had been anticipated for a long time, according to the National Park Service.

The agency stated in a description of the site on its website: "This formation is beautiful, but it is temporary and has a limited lifespan." They added: "The sea arch will eventually collapse into the sea."

However, other arches will take its place as the cliff gradually retreats towards the land." The National Park Service explained that the lifespan of the cliff is determined by a process known as differential erosion, which is a process in which softer rocks erode more quickly and to a greater extent than stronger and more resistant rocks.

Landscapes are continuously reshaped by differential erosion, which is the same process that led to the formation of this arch over five centuries ago. Park staff were aware that the continuous pounding of waves on the sea arch would eventually lead to its collapse into the Pacific Ocean, although they were unable to predict the exact timing of that event.

Hawaii Volcanoes National Park urged visitors to stay away from the edges of unstable cliffs to avoid putting themselves or emergency response teams at risk.