Top 10 Things to See and Do in Australia, page-38

if you look at a giant rock and think, wow !
(Ayers Rock)

then you must see the biggest natural hole in this country
no, not Canberra silly

the Wollomombi hole
https://www.bestsydneywalks.com/wollomombi-falls-chandler-falls/
however, photos/picture do not do it justice, as people at the bottom look like ants


where
Getting to Wollomombi Falls:

Coming in from Armidale, follow Grafton Rd / Waterfall Way for about 40km when you turn into Wollomombi Falls Rd. After 2km turn left at the fork which takes you to the car park with barbecue and toilet facilities.
If you’re driving in from Coffs Harbour / Bellingen, follow Waterfall Way until you make a left turn into Grafton Rd shortly after you’ve passed Ebor Falls. Stay on Grafton Rd for another 40km before making a left turn into Wollomombi Falls Rd.