cocos keeling islands, a territory of Australia about 2000km NW of Perth ive herd are very good, if you go to Ningaloo reef theres a good chance of seeing manta rays and whale sharks.
The egyptian sea is apparently very good and obviously the barrier reef, so many islands and spots to choose from.
Dahab is good but if you can afford take a live-aboard trip down to Ras Mohammed National Park - it will blow your mind!
I also dived Nanuna-I-Ra in Fiji this - the most pristine and beautifil soft corals I've ever seen.
England quarry diving also rocks - gets those skills sharpened when you can't see more than 1 metre in front of you
For snorkelling I'll give Ningaloo Reef another vote. I didn't get a change to dive there, but I didn't have to - the snorkelling was better than any dive I had done on the Great Barrier or Thailand. The coral was excellent, we seen heaps of sharks, manta rays, and fish of all kinds. And what's best is that you can do all of this off the beach. No need for boats or expensive tours, just rent a mask and fins, head down to the beach and go to it. The place to go is Exmouth. I didn't find coral bay good at all.
Maldives (of course) and off the coast of Sabah in Northern Borneo
SImilan Islands for Mantas was great (before Tsunami, should be cleared by now) I went t
ozambique, very remote "King Kong Islands" there, not so travelled. Should you like it cold and scary: CApe Town and the bay there, you can dive off the boat, freeze, and be stunned to see a great (or smaller) white... Needs to be liked.
Just.....Dahab and Ras Mohammed national park in the Sinai in Egypt.
[ Edit: Edited on Dec 25, 2006, at 1:45 PM by wouterrr ]
Sipidan in Sabah, Borneo did it for me. Turtles and sharks galore! Loads of really good macro life too. Don't take my word for it though, it was also Jacque Cousteau's favourite dive site apparently. More expensive than most places in Asia but can still be done without breaking the bank.