When I was 12 my French class had an exchange with another school near Trois Riviere in Quebec which involved 2 flights. During our layover in Montreal our chaperone French teachers drilled into us the importance of showing up at the next flight's gate on time but let us loose for several hours. Three classmates and I went off to explore the terminal together. It was the first time flying for all of us. We headed back to the gate very early since we were such responsible kids but somehow we accidentally wandered outside of the security zone and couldn't re-enter without our boarding passes...which were in the possession of our chaperones. We had security page them. They showed up shortly, looking very unhappy that we cut their adult drinking time short!
Besides that it wasn't until university that I went on short weekend road trips to Toronto with friends where we planned and navigated on our own. We did the trips on Greyhound buses, Via Rail train and car.