I love the phrase going down a rabbit hole, but it got me thinking, do rabbits even dig that deep to begin with? And what organisms (besides humans) might dig deeper that might be even more fun to tweak that phrase with?
Edit: Specified in title/body that I had meant to ask about non-human organisms. Still, there’s some cool info about deep human digs in the comments below for digfolks!
A species of fig (Ficus, family Moraceae) from the Transvaal of South Africa was determined to have roots reaching at least 122 meters - source, google fu