I've done Similans in 2013 and 2014. 2013, it was a better dive, water was nicer, more marine creatures in Richelieu Rocks, 2014, half of the creatures disappeared. Over dive??
In 2013, I did my dive with Similan Seven Sea Club, my guide was a Thai, name Wichay or something.
In 2014, with Khao Lak Scuba Adventures, Ricardo (Spanish dude) was my guide.
Both guides were great chaps. Enjoyed my time with them. Good and responsible.
I witnessed another guide from another boat, not sure which operator, which pissed me! The guide actually used his dagger to 'stabbed' under the rocks just to get a mantis shrimp out of hiding. How irresponsible! We enjoy our dives, not at the expense of other lives. Agree?