I was thinking about that when I was dropping my 6 year old off at some hobbies earlier - it’s pretty much expected to have learned how to ride a bicycle before starting school, and it massively expands the area you can go to by yourself. When she went to school by bicycle she can easily make a detour via a shop to spend some pocket money before coming home, while by foot that’d be rather time consuming.
Quite a lot of friends from outside of Europe either can’t ride a bicycle, or were learning it as adult after moving here, though.
edit: the high number of replies mentioning “swimming” made me realize that I had that filed as a basic skill pretty much everybody has - probably due to swimming lessons being a mandatory part of school education here.
Norway.
Cross country skiing. It’s basically expected for every kid in school to be adaquate at cross country skiing. P. E. classes during winter could often consist of a ski trip, and a couple times per year the schools would arrange ski days with different acrivities on skis.
Learnt this the hard way when moving from Denmark (some snow, but not enough for snow sports) as a kid.
Also no mountains in Denmark of downhill skiing