Hōlei Sea Arch Collapses After Years of Instability
The 90-foot Hōlei sea arch on the southern coast of the Big Island of Hawaii has collapsed into the Pacific Ocean, the U.S. National Park Service confirmed Friday, October 2, 2026. The arch stood within Hawaii Volcanoes National Park. It formed about 550 years ago and was a widely photographed coastal feature. The Guardian
The collapse window is narrow. The arch was still standing on September 23, 2026, when the park closed during Tropical Storm Nolo. It had collapsed by the night of September 27, 2026. The collapse was expected. Park officials had tracked instability in the surrounding cliffs for years. National Park Service
Geologically, the arch was a product of selective removal of material from ancient lava flows. The U.S. Geological Survey described its formation as erosion along cracks and weaker rocks, a process that isolated the span from the adjacent sea cliff. Its fall was attributed to differential erosion. CNN
That process had visibly accelerated. Earthquakes during the 2018 Kīlauea eruption damaged the cliffs around the arch. In January 2020, new cracks prompted closure of the original viewing area, with a safer viewing area opened three months later. Later in 2020, surf from Tropical Storm Darby broke off a chunk of rock from the lower portion of the arch. Each episode reduced the span's structural margin while leaving the overall form intact until late September.
The broader context here is the management problem posed by transient coastal landforms in a high-energy, volcanically active setting. Sea arches are inherently temporary, maintained only while erosion rates across the span and the adjoining cliff remain in balance. At Hōlei, seismic disturbance, wave loading during tropical systems, and progressive cracking combined to narrow that balance over several years. The sequence from setback of visitor infrastructure to partial failure to complete collapse follows a familiar hazard-management arc for unstable cliffs.
Looking at what this means for the park, the immediate questions are operational rather than geological. The site will require reassessment of cliff-edge stability, viewing distances, and interpretation. Arch collapses also alter local nearshore morphology and sediment supply, though the persistence of those effects depends on wave redistribution of the fallen material. For administrators of dynamic coastlines, Hōlei reinforces the value of early setback, continuous crack monitoring, and public communication that treats collapse as a matter of timing rather than possibility.
