I have over 100 tabs open on the Wikipedia app at any given time. There are some things I simply have to know more about. Recent deep dives have included Onfim, Ketchup as a vegetable, and the Cretaceous–Paleogene extinction event.
I recently came across r/knolling and I am now obsessed. I love it so much. Seeing people's trinkets or the things they carry around in their bag is so fascinating. Those things also being organised perfectly just adds a whole new level of bliss.
Hitting the 'sound ID' button and nearby birds being identified by their songs is one of life's greatest pleasures. The rush I get from travelling somewhere new and adding a new bird to my life list. Being able to say "oh, that's a European Starling". I'm 27 and birdwatching (birdlistening?) is my fav hobby.