This 50min dive's entry point is Lake Macquaire 2hrs form Sydney . It makes for a great drift so coincide you entry with the tide changes. It makes for an adventurous exploration of what's left of the bridges since 1988 and even though the viz can sometimes go to 15m take a torch for optimal enjoyment. To kick off the dive follow the channel wall at 7m and out toward the bridge. Swim over the pylons and use the rope across the channel to navigate along. The tide can be strong so be aware of this. You'll see plenty of marine life between here and the second pylon. There's lots of bulk on the ground form the bridges which has gathered some coral and helped break the current a bit. The marine life is truly abundant. By the time you get to the north shore 20 min should have passed. Remember this site spans under a very busy motorway so no surfacing if you loose your buddy.