My wife and I went through US customs at YVR and soon realized that we couldn't get to the aquarium. Is there a way to leave once passing through customs? I have a 6 hour wait until my next flight.
I remember last time I went through US preclearance in Toronto, that there was a sign that said something like, if you pass through preclearance, you must proceed on a flight to the US the same day; and if you leave, you must report to the Canadian Border Services Agency. (I can't find a picture or copy of the text, unfortunately.)
So I think basically, you would have to report to CBSA and go through Canadian immigration and customs to go back to the rest of the airport, and you would have to then go through US preclearance again when you want to board your flight later.