Such a nice comment from a customer on Tripadvisor: 

“Awsome diving high standards of professionalism of staff”
Reviewed 29 May 2012 
Diving with Rainbow instructors in Con Dao is itself great fun and safe experience. I have dived in more than 20 countries and the diverisity, color and shape of corals are as good as it can get. In my view as good as it is in known places such as in the Maldives. However, is not a place to see big games. The samall number of big fish and other animals are well compensated by the incredible beauty of the corals and the beaches around the diving sites.
Istructors make the diving fully safe, fun and relax. While in Can Dao I strongly advice to take a tour to see the Turtle nesting organized by National Park. Rainbow staff can assist you in contacting then
Juan O
Bogota, Colombia

http://www.tripadvisor.co.uk/Attraction_Review-g1024768-d1949574-Reviews-Rainbow_Divers_Con_Dao-Con_Dao_Islands_Soc_Trang_Province_Mekong_Delta.html