Insight into PNG diving, islands and the Sepik

Hey all,
Been great reading through all the posts and definitely picked up plenty of useful info and tips.
We're heading to PNG for a month in June-July and so far our trip looks like Lae-Mt Wilhelm-Goroka-Madang-Sepik River and possibly New Britain and/or Kavieng.
Heard the diving in Tufi and Milne Bay is great but a little choppy and not so good visibility at this time of year.
How is the diving and snorkelling in Madang? Are there some nice beaches off the beaten stretch?
If anyone has dived in Kimbe Bay, would be great to get some insider information about the place and the marine biodiversity?
Thanks to those who have already recommended guides and places along the Middle and Upper Sepik. We'd love to hear any other great experiences and stories along the mighty river.

Thanks loads in advance for any help,

I dove in Kimbe Bay in May 2008. The diversity of Kimbe Bay is said to be the greatest in the world. There are more species of coral there than anywhere else. The water is very warm. I never needed a wetsuit. Temp was 30C if I remember.

I stayed at the Walindi Plantation Resort, which caters to divers. It was top notch.

I did a half day snorkelling around Madang in a small island (I think the name of the island is Wonad). It was very nice and wild.... there were only 4 people on that tiny island (2 of us and 2 other tourists) where the boat dropped us. Snorkelling was OK although not extremely impressive. Some people dove but I do not have any experience in diving.
In Madang itself there is not nice beaches, you have to go further with a boat but a half day trip or a full day trip is not difficult to organize.

Emilia