Just back from a 3 week stay in Australia. I did make one dive in Sydney as well as almost a week of diving in Cairns. Below the details:
Cairns is really a very nice town but not a resort as I'm used to. There is little beach (compared to islands). Even if you drive, the beaches are quite close to the road - still beautiful, but small. Cairns has tons of shops and travel agents. The agencies support about 100 boats that go out to the reef for various trips. I had done some searches online and pre-booked my trips. The town is walkable and there are some great restaurants. There is not really much to do there though unless you book a trip so we ended up driving to the rain forest on off days. That is nice for a dive break but a long drive. I stayed in the Hilton right near the first dock so very close to the big boats. I'd recommend a Hilton stay if you can afford it. There are many hotels of all different classes including a lot of hostels.
I had two day trips with a non-diving spouse. For this, I booked Tusa 6. I would recommend Tusa as a dive boat. The dive area was large, there was plenty of room on board. Food was OK.
I also booked a 3 day stay with Reef Encounter who go to the outer reef system north (across from Port Douglas). I really liked their system. They would send a fast boat out to the reef, then passengers would board a larger vessel with cabins for their overnights. This happened every day in a different location. Still, it means you get to choose how long you stay on board. There was never a problem getting on and off. The dive system was extremely organized. They really knew who you were, got you on board and off. The dives could be unguided but since I was solo, I hooked up with a DM for my dives. There are a lot of inexperienced divers there. In fact, I had more dives than all the passengers and dive guides combined. The guides are young and they can only work there for two years by law. The cabins are the best I've ever stayed in (over 20 live-aboard trips). The food was exceptional & buffet style. You pay for liquor at the end of the week. I brought my regs and computer but rented everything else at a very good price.
The diving imo was just OK where we were. I compare everything to Galapagos so perhaps its unfair to say. On almost every dive, we saw at least one little shark. There were turtles on many dives. The fish life was great as long as you stayed above 20 feet or so. The coral was exceptional; varied and healthy. There seem to be many dive sites with chimneys and tunnels which are my personal favorites so I was in heaven. I went to dive sites like Breaking Patches, Caves, Twin Peaks, Fingers. In true Aussie fashion, they are simply named. Max depths averaged around 50 feet so very shallow. The boat let you do 4 dives a day when you stayed on board so it was perfect for me. Overall, I was impressed with the boats and the coral but not overly impressed with the fish life. Still it was nice comfortable diving.
Water temps were 80's which is comfortable for most but I needed a skin and full wetsuit. We weren't attacked by stinger at all so this time of year seems good at least for that. There was little current where I was.
I had also done the aquarium dive in Manly. I would not recommend this dive to anyone. I've done a fair number of aquariums across the US and some are great. In this tank, you do have the opportunity to see some huge sharks but the space is so small, you can't actually swim. That's right - they don't even give you fins. You need to walk about 10 feet and stand while the cramped sharks swim past you. It was uncomfortable and I felt badly for the fish. Pass on this one.
Cairns is really a very nice town but not a resort as I'm used to. There is little beach (compared to islands). Even if you drive, the beaches are quite close to the road - still beautiful, but small. Cairns has tons of shops and travel agents. The agencies support about 100 boats that go out to the reef for various trips. I had done some searches online and pre-booked my trips. The town is walkable and there are some great restaurants. There is not really much to do there though unless you book a trip so we ended up driving to the rain forest on off days. That is nice for a dive break but a long drive. I stayed in the Hilton right near the first dock so very close to the big boats. I'd recommend a Hilton stay if you can afford it. There are many hotels of all different classes including a lot of hostels.
I had two day trips with a non-diving spouse. For this, I booked Tusa 6. I would recommend Tusa as a dive boat. The dive area was large, there was plenty of room on board. Food was OK.
I also booked a 3 day stay with Reef Encounter who go to the outer reef system north (across from Port Douglas). I really liked their system. They would send a fast boat out to the reef, then passengers would board a larger vessel with cabins for their overnights. This happened every day in a different location. Still, it means you get to choose how long you stay on board. There was never a problem getting on and off. The dive system was extremely organized. They really knew who you were, got you on board and off. The dives could be unguided but since I was solo, I hooked up with a DM for my dives. There are a lot of inexperienced divers there. In fact, I had more dives than all the passengers and dive guides combined. The guides are young and they can only work there for two years by law. The cabins are the best I've ever stayed in (over 20 live-aboard trips). The food was exceptional & buffet style. You pay for liquor at the end of the week. I brought my regs and computer but rented everything else at a very good price.
The diving imo was just OK where we were. I compare everything to Galapagos so perhaps its unfair to say. On almost every dive, we saw at least one little shark. There were turtles on many dives. The fish life was great as long as you stayed above 20 feet or so. The coral was exceptional; varied and healthy. There seem to be many dive sites with chimneys and tunnels which are my personal favorites so I was in heaven. I went to dive sites like Breaking Patches, Caves, Twin Peaks, Fingers. In true Aussie fashion, they are simply named. Max depths averaged around 50 feet so very shallow. The boat let you do 4 dives a day when you stayed on board so it was perfect for me. Overall, I was impressed with the boats and the coral but not overly impressed with the fish life. Still it was nice comfortable diving.
Water temps were 80's which is comfortable for most but I needed a skin and full wetsuit. We weren't attacked by stinger at all so this time of year seems good at least for that. There was little current where I was.
I had also done the aquarium dive in Manly. I would not recommend this dive to anyone. I've done a fair number of aquariums across the US and some are great. In this tank, you do have the opportunity to see some huge sharks but the space is so small, you can't actually swim. That's right - they don't even give you fins. You need to walk about 10 feet and stand while the cramped sharks swim past you. It was uncomfortable and I felt badly for the fish. Pass on this one.