La, IMO on the basis of a few dives you can not come to a conclusion about diving, where you're very much dependent on guide and marine life. Some days can be nice, some days are not that good.

Dives like Koh Doc Mai, Shark Point and Anemone Reef can be excellent, with e.g. frogfish, seahorses, leopard sharks, still plenty of them there, etc.

Other sites like the Similans (sometimes possible in the present greens eason) are truly world class.