Hawaii's 550-Year-Old Hōlei Sea Arch Collapses Into Pacific

The Hōlei Sea Arch, a prominent natural landmark on Hawaii's Big Island, collapsed into the Pacific Ocean between September 23 and 28, 2026, according to the National Park Service. The arch, which stood approximately 90 feet (27 meters) high, had formed around 550 years ago when ancient lava flows from a volcanic eruption carved a vault through cliff edges via differential erosion—a process where softer rock wears away faster than harder rock. The park was temporarily closed during Tropical Storm Nolo when the collapse likely occurred; officials confirmed the arch was still standing on September 23 but had disappeared by September 28 when the park reopened.

The collapse was not unexpected. Park officials and the U.S. Geological Survey had long anticipated the arch's failure due to continuous wave erosion and structural instability. The cliffs surrounding the arch had shown visible signs of weakness for years, accelerated by the 2018 Kīlauea volcanic eruption and summit collapse, which caused damage to surrounding formations. In January 2020, cracks and instability prompted the park to close the original viewing area. Later that year, Tropical Storm Darby's heavy surf broke off a chunk of rock from the arch's lower section. This year's series of severe Pacific storms—including hurricanes Lala and Lowell in August and early September, followed by Tropical Storm Nolo—contributed to the final collapse.

The National Park Service has issued urgent warnings to visitors, citing falling rock hazards and unstable cliffs. Social media posts showed people entering the closed area near where the arch stood, prompting officials to emphasize the serious risk of falling and drowning to both visitors and first responders. The NPS noted that while the Hōlei Sea Arch is now gone, the natural process of differential erosion will eventually create new sea arches as the cliff slowly migrates inland over time. The name "Holei" derives from a small endemic plant in the milkweed family native to the region.