The Night Sky
The night sky is getting harder and harder to see, which makes moments when stars and planets and the Milky Way are visible even more special. I've been lucky enough to see the Milky Way a few times, and the experience of seeing the sky filled up with stars, away from light pollution, was incredible.
If you've never had a chance to see the night sky away from light pollution, I highly recommend that you go try it at least once. If you find a cloudless night, it is not an experience you will forget.