The Hualai River, in China, is apparently the narrowest river in the world, measuring only a few dozen centimeters at its widest point.

At its widest point, the Amazon is more than 6 miles wide during the dry season, and a whopping 24 miles wide during the wet season. It’s by far the widest river in the world, but although there are plenty of other rivers at least a mile-wide at their widest point, width is not a defining characteristic of a river. In fact, there’s actually a river in China so narrow that you can easily step over it. Hualai River, on the Inner Mongolia Plateau in north China, is over 17-kilometers-long but has an average width of just 15 centimeters. At its narrowest, it is just 4-cm-wide.

It’s hard to believe that a river like Hualai actually exists, but according to Chinese experts, it has been flowing through the Gongger grassland for at least 10,000 years. Apparently, it stems from an underground spring and flows into the Dalai Nur Lake in the Hexigten Grasslands nature reserve.

Although some would say that Hualai is too narrow to even be considered a river, the fact is that size is not a distinguishing factor between rivers, streams and creeks. Hualai is a permanent body of water, flowing steadily throughout the year, and it has all the disguising elements of a river, such as a clearly defined basin, flood-meadow, etc.

Hualai is also known as ‘Book Bridge River’, because of a folk story involving a boy who tripped while trying to cross the river, dropping his book right over one of the narrowest parts of Hualai. The book became a useful bridge for the ants that were trying to make it to the other side, and the name Book Bridge River stuck.

Although Hualai River is not particularly wide, it has a depth of up to 50 centimeters.