An article I wrote in Japanese about diving in Ambon just came out.
Not many people have travelled to Ambon since the social unrest there in the late 1990s. I've been there twice now, and I'll definitely be going back. The critter/ muck diving is fantastic, and there are no crowds.
If you happen to read Japanese, or just want to look at the photos, the PDF file is about 3.5MB.
Related post: Ambon Adventure