I have two hobbies that rather neatly overlap each other so quite often I can pursue both at the same time.
One is railways, any railways. While I much prefer steam locomotives I'm not against modern traction, I'm as happy standing on a mainline station just watching the modern trains go by as I am visiting a heritage steam railway. My interest in railways goes beyond real railways and I have a decent size model railway which is based on a Welsh slate line. Like all model railways it's a work in progress and keeps me happily occupied when I can't get out to see the real thing.
The other hobby is photography, stills and video. I'll photograph and video most things, steam trains being my favourite subject But I also like military aircraft, tanks, historic monuments, prehistoric sites, churches, castles etc.
In fact when I go away on holiday I take almost as much photographic gear, plus a laptop so I can check each days haul of photos, as I do clothes.