There are many types of thrill seekers in life.
Some people like to swim, some people like to climb, some people even like to jump off things, but few people have the courage to participate in the illegal activity of "Draining".
Draining, often done by Urbexers (Urban Explorers) is the act of exploring drainage systems, and in Sydney's case, Storm Drains, which are drains designed to collect storm water.
The Fortress has many entrances around town, and boasts an impressive ten stories below ground that stretch over two kilometers.
Be warned though, flash floods are a very real threat and there have been a few deaths in the Fortress over the past few years.
But if you're looking for a thrill, and want to see something that few others ever get to see, grab your torch, grab your camera and wait for a sunny day and explore the depths below....