One of Hawaii's most photographed coastal landmarks is gone. The 90-foot Hōlei Sea Arch at the end of Chain of Craters Road in Hawaii Volcanoes National Park was still standing on Wednesday, Sept. 23, but had collapsed into the Pacific by Sunday night, Sept. 27, the park said in an Oct. 1 news release.

No one saw it fall. The park said the exact time is unknown and the collapse may have happened while the park was temporarily closed during Tropical Storm Nolo.

For the many visitors who drive the winding road down to the coast, the loss changes one of the park's signature stops. It is also a reminder that the dramatic lava cliffs along this shoreline are constantly breaking down, and the park says the edges can give way with no warning.

A Landmark Carved From an Ancient Lava Flow

The arch was cut into a sea cliff made of lava that flowed to the coast about 550 years ago, Hawaii News Now reported, citing the park. Pacific waves pounding that cliff carved the opening through a process called differential erosion, Popular Science reported, citing the National Park Service.

Differential erosion happens because rock is not uniform. Lava cools in layers of different hardness and fracture patterns. Waves wear away the softer or more cracked layers faster than the stronger ones, hollowing out a gap while harder rock above stays in place as a bridge.

That bridge never lasts. The same waves keep attacking the base and sides, and cracks spread through the rock overhead. Eventually the span becomes too weak to support its own weight and drops into the sea, often leaving behind a lone pillar called a sea stack.

The arch's name comes from hōlei, a small native plant in the milkweed family, according to CBS News.

Years of Earthquakes and Surf Took Their Toll

The collapse did not come out of nowhere. According to the park's release, earthquakes during the 2018 Kīlauea eruption and summit collapse damaged the cliffs around the arch.

In January 2020, the park closed the original viewing area after new cracks and instability appeared, and it opened a safer viewing area farther from the edge in March 2020. Later that year, massive surf from Tropical Storm Darby broke off a chunk of rock from the lower part of the arch, the park said.

Nolo's role is not confirmed. Popular Science reported that Nolo reached Category 3 hurricane strength at sea and brought more than a foot of rain to parts of Hawaii Island in late September. The park has said only that the arch could have fallen during the closure, and no one has documented which wave or storm delivered the final blow.

Young lava coastlines like this one are especially prone to sudden failure. A single cliff can contain dense flow layers stacked on top of rubbly, broken layers that waves scour out quickly. Once the weak layers at the waterline are undercut, the heavier rock above can break away along existing cracks with little visible warning.

The National Park Service had long warned that the formation would not last forever. "This formation is beautiful, but temporary, and has a limited life span," the agency said, as quoted by CBS News.

Popular Science reported that the park also noted that new arches can form as the cliff slowly retreats inland, so the coastline may one day carve another.

Unstable Cliffs Put Visitors at Risk

The bigger concern for the park now is people. Coastal cliffs along this stretch drop straight into deep, rough water, and the rock is riddled with hidden cracks.

"Visitors are urged to stay back from the unstable coastal cliff edges which drop off vertically into the ocean and present a serious falling hazard," the park said in its release.

CBS News reported that the park also said photos on social media show people entering the closed area, "putting themselves and first responders at great risk." A rescue from these cliffs is dangerous for rangers and firefighters, and a fall into heavy surf can be fatal.

Those at greatest risk include visitors who walk past barriers for a closer photo, people standing near the edge during high surf, and anyone exploring the coastline after dark when cracks are hard to see. Families with children should keep a firm hold near any cliff overlook.

Planning a Visit to the Coast

Visitors should follow posted closures and use only the designated viewing areas. Warning signs of danger include fresh cracks in the ground, loose rock, sea spray reaching the cliff top and waves surging higher than expected. If any of those appear, move away from the edge immediately.

Check the park's website and alerts before driving Chain of Craters Road, especially after storms, since conditions and closures can change quickly. Rangers at the Kīlauea Visitor Center can explain which coastal areas are open.

The arch was not the only feature shaped by this coast's constant change. The same forces built new land during past eruptions and keep reshaping it today, which is part of what makes the park's shoreline so striking and so hazardous.

Several questions remain unanswered, including exactly when the arch fell and how much of the remaining cliff is now unstable. The park has not announced any new closures tied specifically to the collapse.

The bottom line: a 550-year-old landmark has followed the natural life cycle of every sea arch, possibly helped along by storm surf from Nolo. Visitors can still see this dramatic coastline, but only from a safe distance and only where the park allows.

What Readers Want to Know

When did the Hōlei Sea Arch collapse?

Sometime between Wednesday, Sept. 23, when it was last seen standing, and Sunday night, Sept. 27, 2026. The park said the exact time is unknown.

Did Tropical Storm Nolo cause the collapse?

It may have played a role. The park said the arch could have fallen while the park was closed for Nolo, but the cause has not been confirmed.

How old was the arch?

It was carved into a cliff formed by a lava flow about 550 years ago and stood about 90 feet tall.

How do sea arches form?

Waves wear away weaker layers of rock faster than stronger ones, a process called differential erosion, eventually cutting an opening through the cliff.

Is it safe to visit the area?

Visitors can still view the coast from designated areas. The park urges people to stay back from cliff edges, which can collapse without warning.

Will a new arch form?

Possibly, over long periods. Sea arches eventually crumble, but new ones can form as waves keep eroding the cliff inland.