Just got back from a 10 day cruise of the Andaman Sea.
Phi Phi Islands (Bida Nok and Bida Nai) very nice soft corals, lots of fish.
Koh Haa, lots of soft corals, lots of fish
Sharkpoint and Anemone Reef , see above
Similan Island, only two small spots closed, the rest ok for diving. Not many soft corals, mainly big boulders and interesting scenery. At some places dead hardcorals in the shallows, (Island 9)
Koh Bon , very good Manta action, lots of fish, but also dead hard corals on the western site. Great if you see mabtas
Koh Tachai pinnacle, big boulders, tons of fish, also there we had two mantas
Richelieu Rock- world class, lots of macro (harlequin shrimp, sea horse, ghost pipe fish)
Surin Islands- most of the places are closed, I have been there two weeks ago and the diving was not good anyway. So uyou dont miss much.
I thiunk the only negative thing is that there are so many boats with snorkelers and divers out there. We had 8 lob on richelieu rock, 11 lob in Koh Bon.
So the dive guides need to plan good that you avoid the other 100 divers.
Oue season is finished we are off to Andaman Islands and have a look what the season brings over there