I remember the feeling of awe the first time I dived after certification, I'm still waiting for it to wear off, but one of my most memorable dives, was when I worked as a dive guide; I'd been allocated to dive with a very nervous couple who had done their whole certification (theory and practical sessions) in just 2 days about a week earlier.
I planned a nice easy 10-12 meter dive with them and after swimming with the resident barracuda school which was in the shallows that day, I was leading them over a broken coral patch (normally this is a slightly deeper wall dive to miss the broken coral) to the better coral when we came across 2 octopuses mating, the colours and patterns that moved across them in a continuous wave were just amazing, it was hard to see a break in the patterns from one to the other.
To finish the dive, when we surfaced, the smile on their faces was just fantastic and the first thing the lady said was "I can't wait to dive again".
Being able to dive is brilliant, but being able to share that feeling with someone else, priceless.