Kadavu is probably the most traditional of the Fiji islands. Matava is on the southern side of Kadavu about 1 hour or so boat ride from the airport. It is isolated and secluded. The bures are fairly traditional thatched huts that blend in very well with the rainforest setting. I much prefer this style of accomodation to the big touristy resorts found on the Coral Coast for example. Now, my information on Matava is not completely up to date since it is now 9 years since i stayed there (although I was on Kadavu in June of this year). When we stayed there the resort was relativley new and they were still exploring the local dive sites. They certainly had some good dives on offer, and i suspect they may have found more sites since I was there. It is a bit hard to remember back nine years to compare the quality of the diving with that which I have done more recently in Fiji and Vanuatu, but certainly at the time I was very impressed with the dives. We saw sharks on several dives (white tips and grey whalers), and other large fish (eg barracuda, trevally, bumphead wrasse etc.). There were some great gorgonian fans - some of the biggest i have ever seen. I know on some of the dives we saw large numbers of soft corals, but possibly not as good as the soft coral we saw at Dive Kadavu recently - it is hard to remember accurately enough to make comparisons.
The water temp on Kadavu seems to be a little cooler than other regions of Fiji. Both my Kadavu visits have been in winter (June/July) and we were getting cool towards the end of dives despite full length 3mm suits. Towards summer the water temp will obviously be a good bit higher (but the summer months themselves carry the risk of cyclones). Unfortunately I can't provide a comparison with the Bligh Waters since I haven't dived there - but I have heard it is good diving. For an adventurous holiday in a remote setting Matava would be a good choice.