Troubridge Island Lighthouse, South Australia

Sandbags like these could keep the sea from further eroding structures like the Troubridge Island Lighthouse, but time’s running out.

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The Troubridge Island Lighthouse on Troubridge Island, off the Yorke Peninsula in South Australia, was built in 1856 to guide mariners past the Troubridge Shoals. Made of cast-iron, the round, 79-foot (24-meter) high tower has wide, horizontal red and white stripes. It's made it through an earthquake and a fire, but the persistent erosion of the sea is threatening its existence. The sands are constantly shifting, and the lighthouse now stands at water's edge. When the seas are high in winter, the foundations are in danger.

The lighthouse became less important when a new lighthouse was built on nearby Troubridge Hill in 1980, and it was taken out of service sometime around 2002. Sandbags have been used to hold the sea at bay, but unless something more is done, it's probably only a matter of time before this lighthouse disappears for good.