Did you know that

the Nile (6669 km) is the world's longest river, followed by the Amazon (6436 km) and the Mississippi (5969 km)? Or that the longest rivers in Asia and Africa are the Yang-Che-Yang (5471 km) and the Congo (4373 km) respectively? Or that the Murray and Darling River in Australia (3717 km) is the eighth longest in the world, beating Europe's longest - the Volga (3685 km) and the Danube (2850 km) - into ninth and tenth place?

No? Well you would if you'd been helping Emily revise for her geography test tomorrow.

And that's just the rivers! There are lakes, too! (Whatever you do, don't get me started on lakes! Did you know there was a Lake Baikal? I've never even heard of Lake Baikal...)