Hawaii's famous Hōlei Sea Arch, a 90-foot-tall (27.4m) lava rock structure that formed about 550 years ago, has collapsed into the Pacific Ocean.

collapse's exact time is not known. The arch was still projecting into the water from the coast of Volcanoes National Park on 23 September, but was gone by 27 September, the National Park Service (NPS) said. BBC reported.

"The coastline flanking the sea arch has shown signs of instability for years," NPS, which warned in 2021 that the arch would eventually crumble, said in a statement.

Located at the end of Chain of Craters Road on the island of Hawaii, also called "the big island", the formation was a popular - and heavily photographed - tourist destination.

The arch is believed to have fallen when the park was temporarily closed during Tropical Storm Nolo last weekend.

The park service said earthquakes during the 2018 Kīlauea volcano eruption and summit collapse had damaged the cliffs near the arch