Darwin’s Arch, a famous, photo-friendly rock formation in the remote Galápagos Islands, collapsed Monday because of natural erosion, Ecuadorian officials said.

The collapse of the natural archway in the Pacific Ocean, about 600 miles west of continental Ecuador, left a pile of rubble between two pillars.

The waters around the arch are known as a destination for divers, with tours from the main islands offering the opportunity to spot sharks, turtles, manta rays and dolphins. The arch was less than a mile from the uninhabited Darwin Island; both are named after Charles Darwin, the scientist whose study of species on the islands in 1835 influenced his theory of evolution and natural selection.

Monuments and islands everywhere are under threat of erosion, sometimes from the simple passage of time. But UNESCO, the U.N. Educational, Scientific and Cultural Organization, has warned that the Galápagos Islands are one of the world’s most vulnerable places to the effects of climate change.

The islands sit at the intersection of three ocean currents and are vulnerable to the El Niño weather system, which causes rapid warming of Pacific Ocean waters. The warming waters threaten the very species that Darwin observed.

Easter Island, also in the Pacific Ocean, stands to be eroded by rising waters, threatening its residents and famed moai statues now within the reach of waves.

The Galápagos, once a destination for only well-off travelers unfazed by the islands’ remote location, had seen an increase in tourism before the coronavirus pandemic, with visitor numbers jumping 90% between 2007 and 2016. That has concerned some conservationists, who worried the extra visitors would put pressure on the islands’ infrastructure and encroach on animal habitats.

In 2018, a group of tour operators expressed concern about the influx of tourists, saying they could harm not just the wildlife but the islands’ landscapes and beaches. And then there’s the misbehavior: In March, officials at an airport seized 185 baby tortoises wrapped in plastic and packed into a suitcase headed for continental Ecuador.