When I first began surveying the greatest of the world (as opposed to 'in the world'), I thought only that the largest of lakes and all of the seas would serve; that a puny pond is not likely to have anything of impressive scale.
But, while deciding the largest stream is too much like engaging in a pissing contest, Billabong Creek brooks no argument in capturing long waterways that are not rivers.
The largest mountains around the globe and the exceptional Alps and Himalayas are defined by their height above sea level. If you count height from the seabed, the tallest mountain is Mauna Kea. While Chimborazo is the farthest point from the Earth's centre.
The steepest hill in the world is in neighbouring New Zealand.
The world's lowest elevation not under seawater. Not the Dead Sea but the Bentley Subglacial Trench.