Definitely HS. Being the overprotective mother I am (just ask Weeburt), probably 16, minimum, and then only with- the easy child-est of PCs equipped with- cell phone and global positioning device in shoes.
While I know I grew up in a different era, if not safer then at least the underside of life was less well known, I'm simply *appalled* that my parents let me go to the mall with- one friend, unchaperoned, at the ripe old age of 12. We're talking for the entire day. My poor kids.... they'll probably be 25 before I let that happen (I know, dream on, LOL).
But a theme park... urg, yes, definitely older HS age.