Thanks for your comments.
I had had the same idea of diving caverns(caves) of Sardinia for a long time. Finally I did some research to locate dive operators. The single best dive operator listing can be found here: http://www.madebysardinia.it/diving
The key words I searched for were: Grotta = cave, Bombole = tanks, bi-attacho = Dual valve.
I did my diving with a company called Protec Sardinia located in Cala Gonone on the East coast near Dorgali. Their web pages in English and German are here: http://www.protecsardinia.com
For certain weeks they do offer a live-aboard option, but, I was living at a family-run medium-class hotel "La Playa" in/next to which the dive center is located. Very convenient. This is just a couple minutes from the harbor. With their RIBs it takes 15-30 minutes to access the cave sites. Of course there is the normal loading and unloading of tech gear that takes a while. Thus the day begun at 9 am by kitting up and loading the van and we would be back by 4 or 5 pm.
The operator has twin 12 liter manifolded tanks plus stage tanks, all with DIN valves. They have air, oxygen, helium and mixtures. I didn't see an helium analyzer, so you might have to take your own if you prefer trimix. They also support CCRs provided that you have the right CCR training for caves. The majority of the caves are 5-25 meters deep. But there are also 40-80 meter depths and uncharted caves if you prefer challenges.
I used a 1960 lumen Green Force LED lamp as my primary lamp (as seen in the video). For the mainly white-walled Grotta del Fico this was good enough for videography. However in some of the black-walled caves you really would have needed more light. For additional videos, please see the Sardinia labelled videos by http://www.vimeo.com/slawekpacko
