The first of mine would be at an observatory in a little country town 100 odd kilometers from Perth city. Its out in the bush and out of the pollution (both smog and light). Easily the most stars I've ever seen in my life, surrounded by absolute and complete blackness. A whole strip, consistent with the plane of the galaxy stretching from horizon to horizon, heavily populated with as many bright dots as can be imagined. They had some world-class telescopic equipment there also, allowing me to view, among other constellations, Saturn's rings. It left me with such a profound feeling of insignificance.
Coupled with a talk from some leading physicists about future experiments to be held at the facility regarding tracing the big bang's energy, it definitely sparked an interest in science as well, which no doubt helped me through my final year of high-school, and more importantly, helped to clarify my own beliefs about life, the universe and existence.
The other occasion(s) is any time that I'm at the beach. I'm fortunate where I live to have some world-class beaches, featuring the purest white sand, brilliant surf and incredible native wildlife. The sheer beauty of the place, especially if you're far enough removed from civilisation to have practically the whole place to yourself, is brilliant. And yet, its almost nothing compared to when you get into the water. Surfing (of the body variety, I never had the patience to learn to stand

So what about the rest of you? Any moments that have left you breathless, inspired, awestruck?