Just come back from 2 weeks holiday in Koh Samui (Skegness really!!!). This is an amazing Island. Vey cheap once you are there for food and drinks!!
Megs and myself completed 5 dives over 2 days. We had another days diving booked but their boat was broken so they cancelled it Bo Bo!!! It would have been read for Wednesday but we were due to fight thursday morning so could do it.
The diving was very good. The water temp was 30 degrees, even down at 20m!!!! We visited 3 sites - Sail Rcok, South West Pinnalces and Shark Island (no Sharks). The diving was on reefs. They were like a small Red Sea reef. There were many different types of fish and coral but no really large fish, Whale Sharks or Mantas.
The diving is not cheap due to the large amount of travel to get to them, 2-3 hours sailing!!!!
Ive put a few pics below -