One of Australia’s oldest iron ore mines has spent the last four years under water.

Almost 70 million tonnes of high-grade iron ore was mined by BHP from Koolan Island from 1959 to 1993. At its peak, it was home to almost 1,000 people and had a school, police station, shops and, for a time, held the record for the world’s longest golf course hole which doubled as the island’s airstrip. It had successfully passed the 20-million-tonne milestone, before the seawall collapsed in 2014.

The Koolan Island mining operation was mothballed in 2014 after its seawall collapsed, flooding the mine’s main deposit which lies below sea level.

Mount Gibson Iron has invested $170 million rebuilding the seawall to restart its Kimberley Coast iron ore mine. “But since then we have taken turtles out, there have been crocodiles active around that area [and] in the pit there are some fish, sharks and the occasional ray.

“We will look to work with the traditional owners, the Dambimangari people, to remove those creatures back to the ocean, as we get lower water levels shortly.”

Koolan Island was one of the first iron ore mines in Australia, established more than 50 years ago by mining giant BHP, along with the neighbouring Cockatoo Island.