"Tanto", a diver based in Italy, just posted this on D-net:
"I've been diving the islands of Croatia for many years, always from private boats (RIBs or Motoryachts), more or less everywhere, even in (partially) prohibited areas like Kornati or Vis.
The water is clear, usually 20-30 meters of visibility, there are many wall dives, some breathtaking like walls going from 2/3 meters (where you would anchor the boat) straight down to 60, 70, 80, 90 meters or more. There are also many wrecks and many caverns.
To my surprise I have seen diving centers taking trimix and even rebreather divers to wrecks like the "Francesca da Rimini" and that was two years ago.
In the past a 10 GBP tax would grant a one year diving permit, now the law has changed, that tax only works if you go diving with authorized diving centers, otherwise the tax is 200 GBP or so.
I wouldn't know which diving center to recommend as I've been always diving with my friends, but with Google's help you might find what suits your needs.
The water is still very cold in August below 15/20 meters (14°) and if you do deep diving a drysuit makes it nicer. In June is far colder but in October/November can be much warmer (16/18° down to 60 meters).
The best walls are in the Kornati park, wrecks are everywhere, you don't really see much fish, but the rare encounters can be moving, like when I was able to stroke a Moon fish which came right to see me (Borovnik island, huge container shape rocks at -65).
Here and there you can still see the red coral, I saw a lot in the outer wall of Lavsa at -87.
Some of the best dives are a little advanced and difficoult to locate, like the pinnacle (from -70 up to -30) between Garmanjak and Sestrice.
All in all some of the best mediterranean diving, in my opinion."
You can contact Tanto at:
tanto_sanmai@yahoo.it