There's a lake that's a perfect circle - Apparently.
Lake Gairdner in Australia is a saltwater lake that has a circular shape with a diameter of approximately 14.5 kilometers. Measuring the lake's circumference in 1955, surveyor Eric Thomas found that it was a perfect circle, with an error of only 0.3 meters. This unusual shape is thought to have been caused by a combination of tectonic activity and erosion over millions of years. The lake's circular shape has been verified by multiple surveys and is a notable geographical curiosity.