Best Warm Water Diving

If you go to Belize, go to Cheers restaurant for good food and tell Chrissy that Ryan Barker sent you. 

Umm, Ryan, if someone said  that would they get  get good service or a slap on the face.   
I don'the dive but a friend that does said that Belize was his favorite place

Everything I read EXCEPT the Barrier Reef is great.  I like Akumal and such off the Yucatan.   The Barrier Reef would probably be good IF you  DO NOT USE the commercial dive companies and their live aboard "cattle boats"  Thousands of divers per day in a two mile or so stretch.  The coral and stuff is beat to death, the equipment weak and they accept no responsibility for anything.  It was the worst diving experience of my life.   Australia itself is incredible and the people are amazing.  If you get there hire a special boat don't go where the others go. 

Belize is pretty fantastic. relatively close and inexpensive to get too. the reef and other nearby places of interest are incredible. the cattle call dives are of course just that. nevertheless those are entertaining and you can get into much better diving and spearing (where allowed) in the areas not visited as often. it takes some coin to do that but nothing outrageous and tickets to BZ can be found inexpensively. plenty of sight seeing for the average snorkeler/diver and plenty of big fish for up to the most advanced spearo (again if you know where to go). theres many islands to explore and inland theres a famous ruin, Lamanai, that is a great day trip. enjoy!