In case someone is interested, the Clearly Cayman dive resorts are offering a special 2 week Expedition package during the last 2 weeks of September.
I'm just posting because it is kind of unusual, the first time I've seen this. The offer includes 2 weeks on 2 islands (Little Cayman and Cayman Brac) and all meals and transfers and 42 scuba dives, including some dusk and night dives and special dives like the Russian Frigate Wreck. They will transfer you by boat between the 2 islands.
Just in case someone is looking for a short notice dive trip in September, but I don't know if they still have availability: