Oh and as for most amazing dives, here are three recent ones. None involving nearly getting eaten by sharks thankfully:
Melbourne: seeing several blue ringed Octopus, including two mating right at the end of the dive. I still hope we didn't cause coitus interruptus.
Maldives:
Maaya Thila: night dive, with lots of grey reef and black tip reef sharks. Hitherto I'd always been nervous of night dives, period. But this was the one I felt totally at home in, and with sharks literally swimming between my legs it was a good time to find that feeling. Slight jolt of adrenalin on seeing 6ft barracuda towards then end of the dive sitting motionless. Looking back at my video that moment looked all very blair witchy, as I realised what and how big and silver it was and when it moved well it was jerky camera time. What a wuss.
Maldives again:
Can't recall off hand the site, but fairly famous or well known hammerhead site. Requires early (5am) start. Think it's in North Male Atoll. Anyhow, after a while at 20m waiting for some action it became clear it wasn't going to happen. So I started paying attention to the tiny lights in the blue around me (it is a very blue in open water dive, no reefs walls etc). So these little tiny lights, violet and magenta were gorgeous. They were all around, everywhere. So I reached out to touch one. As my finger approached one, the light went out and it skiddled (new word by me) 2 cms to the left. Reached out to another, same thing. Every one that I reached out to made the same behaviour - turn the lights out and skiddle sideways. It was like a combination of The Abyss and The Simpsons. Anyhow it was pure lovely and I totally engrossed myself in it. And then the hammerheads came. I had hardly any no deco time (we'd been at 20m for 45mins or something, can't remember) and they appeared below us. Couldn't help myself and sank down to get close. They came close by and my heart only raised throuh pure thrill. I was annoyed to hear my watch beeping at me. Then they slid into the depths and gave me a good excuse not to get into trouble with the guide. That was a magic dive too, as much for the little bio-luminescent scaredy-cats as the fat hammers.
But every dive where you're flying and breathing under water is a an amazing experience.