I would like to nominate the cache by Calypso62 - Building Bridges to Pittsburgh GC6Y611 for the December 2019 geocache of the month.
This multi takes you all around Sydney Harbour gaining coordinates and codewords. The catch is you have to teamup with a US cacher in Pittsburgh who works with you to solve Building Bridges To Sydney from their end. It isn't a multi that will be solved and found in a day as you message back and forth to your buddy, providing the WPs and codewords for each other that will eventually get you to GZ.
There are 5 WPs, and each WP around Sydney Harbour is a gem in it's own. They all take you to great views across the water and the placement of the clue is identical at each stage. The difficulty for most is finding a Pittsburgh partner, but by posting a WRITE NOTE on both pages, someone will eventually join up and assist. Or you can do as I did, with the approval of the CO, three of us in Sydney worked with a US buddy at once. And the rare "Teamwork Required" attribute gets added to your collection.
Of course, GZ is a beautilful spot to end this merry chase and the cache container is up to the usual high standard of Calypso62. It currently has 11 FP (69%). Along the way, you learn a little bit about the history of Pittsburgh, and you also get to work out the GZ for the sister cache in Pittsburgh, if you ever get over there to find it!