Could be a hobby, a field of study, culture, or anything :P
Were there things that you were deeply interested into, much than 'usual'?
Things that I have been interested deeply are, to name some from top of my head...
- Birds. Since meeting a teacher in elementary school who was an expert in them, I read bought field guides and reference books about them. I used to draw them a lot, and had a bird feeder outside until my family moved to the city where I couldn't have it anymore. Though I am not into the topic as much as when I was little, I still read about them often and enjoy watching documentaries about them.
- MLP. ...see my avatar and I used to have them in my signature often (might again soon). I saw all of the eps so far and it's been great!
- Rock music. Recently I'm into it like crazy. I knew groups like Linkin Park, Green Day, and Evanescence for a while and have liked their songs, but recently I've been obsessed with System of a Down's songs.