Add one item to my list of things I hope to see or do before I die: the tiankeng of China. These sinkholes are mindbogglingly huge, and apparently were known to very few people, even within China, until the last decade.

This is the planet our species evolved on, and it still manages to stagger me with the things that we don’t even know about it. Can you imagine the wonders we’ll find, if and when we ever manage to travel to another one?