where is the best diving site in the world?

that depends on what you are seeking to experience in a dive,so many varieties,personally as a dive instructor who has gone to a lot of sites,i still prefer the area around sipadan,good reason why its considered among the top 5 dive destinations in the world.Mainly coz it can cater to almost any diver's preference, whether it s big creatures you want to encounter or hunt for tiny macro critters,it all there.I love hunting for small creatures to see and most of the very special critters u normally see in dive journals can be found that area.Sipadan for big stuff and Mabul for weird n small critters,all in one neighbourhood. Your question is bit difficult to answer because every diver have their own preference,depending whether its corals or creatures,most beautiful coral formations i have encountered are in my home based island of redang malaysia,best and most diverse marine creatures encounter is at sipadan area.But if it is narrowed to only 1 specific site ,then for me its a site called koh saweng off Koh Lipeh Thailand. Mind boggling soft corals growing on huge boulders shaped like christmas trees,pristine and full of energy...beautiful n brilliant!