On the computer science side of things, my favorite topic is computational complexity from both the theoretical and practical points of view. I like the process of designing fast algorithms and implementing them efficiently.
In my free time I do rock bouldering and calisthenics. I also like reading popular science books: some my favorites are "How to Hide an Empire" and "The Sixth Extinction." I use GoodReads to keep track of books I have read and want to read.