Secret underground tunnels discovered below water connecting Antartica to Australia

A list of Secret Entrances and Possible Underground bases
https://www.abovetopsecret.com/forum/thread217797/pg1

A book called Entrances to Subterranean Tunnels “Underground Alien Bases” (UAB) ISBN: 0-938294-92-X (UAB) which purports to list
all the known underground entrances to bases. Here is where they are!  – http://www.ufos-aliens.co.uk/cosmicunder.html

https://allnewspipeline.com/Underground_Tunnels_Unexplained_Booms.php

8 August 2011: The massive European network of Stone Age tunnels that weaves from Scotland to Turkey

https://www.dailymail.co.uk/sciencetech/article-2022322/The-massive-European-network-Stone-Age-tunnels-weaves-Scotland-Turkey.html