Measuring Australia in lengths of around 310 miles (500 km) gives you a perimeter of around 7,800 miles (12,500 km). But the CIA World Factbook says that Australia's perimeter is closer to 16,000 miles (25,800 km)! Depending on how you measure them, coastlines can vary in length to a degree that seems preposterous. For example, you could measure the coastline of Maine with an exacting, one-centimeter-long stick, and then measure the coastline of California with a much longer stick that wouldn't allow you to probe its bays and inlets. In this case, the coastline of Maine could definitely come out longer than the coast of California! Coastlines tend to look like fractals as you zoom in on them, with minute outcroppings and crevices that will increase the length of your result the more precise you are.
The Coastline Paradox Makes It Almost Impossible To Measure Australia's Perimeter
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Key Facts In This Video
Erosion has caused Australia's uneven, craggy coastline. 00:22
Depending on the measurement you're using, estimates for how long the Australian coastline is can vary widely. 00:32
The Koch snowflake has a finite area but an infinite perimeter. 01:20