1st Time Visit to Oz...March 2018...Need Victoria dive recommendations

Hello All!
I'll be visiting AU w/ wife this March. We'll be spending most of our time driving the Great Ocean Road in Victoria. She does not dive, but I can't make a vacation down under and NOT dive! I'll probably only have one day to dive, so I want it to be good. Any recommendations along that route? I'll need a hired dive boat dive with all equipment, so I would appreciate any advice as to sites, dive operators, tips on diving those waters, etc.
Thanks!!!!

G'day!
The Great Ocean Road is spectacular because it has been eroded by violent seas from the roaring forties. This is the same reason there is little in the way of diver services in the area. Pity, as it is also known as the shipwreck coast! The only reliable diving activity in that region is at Port Phillip Heads, near the start of the Great Ocean Road. The diving in this area is spectacular, and with the small entrance to a large bay, it is rare that all diving is cancelled. There are a number of good charter boat operators, but as you will need all your gear, contacting one of the shops in the Geelong area is your best way to organise everything. Depending on your experience, they may require you to do a check out dive with a DM to be sure you can handle diving in a thick suit (water temp will be around 17 dec C).

Port Phillip Heads has some of the most diverse and colourful diving in the world, and worth the effort to experience it. Here is a little sample vimeo.com/119824117

Alan