Hello!
We live in Melbourne and have made a couple of dives around the country.. here's our favs:
1) Yongala Wreck / Townsville / Queensland
- not your typical wreck, this has crazy wildlife
- lots of schools, supersized everything - biggest bony fish in the water (Queensland Grouper)
2) Navy Pier / Exmouth / Western Australia
- military pier, lots of schools of everything
- great dive site for everything under the ocean
- must book in advance, dives depend on tides
3) Cod Hole & Coral Sea - Great Barrier Reef / Outer reefs
- need to do via liveaboard, min 3 days
- get to play and feed with potato cod.. haven't done but want to!
4) Other stuff @ Ningaloo / Western Australia
- great isolated beaches, snorkelling
- diving is great with whale sharks when in season (march - june)
- lots of manta rays in season as well
5) Rapid Bay Jetty & other sites in South Australia
- get to see leafy sea dragons, which are relatives to sea horses
- awesome vis in summer, but can get cold
Any questions around South Pacific, fire away

~ Frank