Considering this subreddit has people on both sides of the gender spectrum (masculinity and femininity), and all sides of the political isle, this is a subjective question.

What hobbies in a potential partner of the opposite sex make them more attractive, is what I mean. And why are they attractive in the first place?

And for me personally as a man, it's martial arts or learning anything involving weapons. Swordsmanship, sojutsu (Japanese art of wielding the yari spear), knife fighting, archery, guns, et cetera. But one hobby I find EXTREMELY attractive is hunting. If a girl has the boobs to hunt and kill deer, feral hogs, or (insert random animal here), she's wife material for sure.