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.
In the dry SW US the answer is drink water when it’s 100F or worse 115F+. Having a half liter of water from the hotel for the half day mountain hike, or pounding a half gallon of ice water and throwing up five minutes later. Your body doesn’t tell you when you should drink, it tells you when you are already behind on drinking.
This is no joke. Even experienced hikers won’t bring enough water for their trek and will end up either being emergency heli-evac’d out or just plain die.
I just carry a half gallon thermal jug with me all the time. Hiking or not. If my mouth feels the slightest bit dry, I need to drink more water. I tend to piss clear, or very pale yellow cause of this, but the upshot is that I was fine wandering around Anzo Borrego national park, and two of my friends (who thought that my idea of covering myself head to toe in jeans, a trench coat, and a trilby was a bad idea,) damn near got heatstroke. I basically threw my water at them when I noticed they weren’t sweating anymore.
This is a real killer. People have no idea and tend to overestimate the risk from wildlife and underestimate the risk from weather conditions and exposure. Far more people are killed by hypothermia caused by extreme heat or cold than anything else in North American wilderness areas.
I’ve been part of my local SAR community here in Oregon for decades now and while we don’t have to worry so much about the heat, what gets people here is the cold.
If you are somehow lost or stuck in the high Cascades at night without adequate clothing or a heat source, you are in big trouble, especially if it rains or snows, both of which can and will happen even in the middle of summer.
River crossings are also a big danger since the current is always much stronger than it looks and the water is near freezing and if you fall in and don’t have dry clothes and it starts to rain and blow, you are fucked.