I've had some interesting experiences clearing customs both directions in the Islands, all in boats. Many years ago, Wife 3 and I boated from Friday Harbor to Victoria, where in the harbor there's a tiny shack to check into Canadian customs, with a phone. We were required to wait until a pair of very young officers, a man and a woman, came to "check out" the boat--but all they did was ask half a dozen questions, and cleared us.
Then on my "Ultimate Small Boat Adventure" (still available through Barnes & Noble, only $15.95

) in 2001, I had intended to check in at Nanaimo, but I was so worn out by the time I got somewhat past Sydney that I stopped at a harbor which had no check-in for customs, called them, and they graciously told me to check in in person at Nanaimo the next day, especially because I had my "boat gun" (12 ga. Mossberg SS short barrel) with me. So I did, and I was allowed in with my shotgun because I intended to use it as "protection from wildlife", since I was camping. The customs officer who accompanied me back to the boat did have to confiscate my Washington apples, however.

So then a few years later, current SO and I rented a Nordic Tug in Anacortes, WA, and cruised first to Friday Harbor and then to Sydney. At Sydney, when I told the customs gal on the phone that I had my shotgun, she said that a couple of officers would have to check us out. They came, and unfortunately instead of saying "protection from wildlife", I just said "self-protection". Whoops! Not allowed. Either confiscate the gun (permanently) or return to the US. We opted to return to the US.
But pup dog needed a break, so both officers accompanied Mah Woman to a grassy spot with the dog--leaving me at the boat with the shotgun!
But now we were required to check in at Roche Harbor--where I was given a lot of steely stares by the huge (like about 6'6", 300 lbs) US Customs officer--and because he'd gotten an email from Canadian Customs, he had to come aboard to see the shotgun to make sure I still had it! (why?)
So fast forward to a couple of years ago, when we again rented a Nordic Tug. This time, somewhat smarter, I had left the shotgun at home. So we arrived at Sydney, I called on the Customs phone at the dock, and upon identifying myself, the gal said, "Tell me, sir, do you have your shotgun with you this year?" But otherwise, she was friendly and gave us the customs number to attach to the boat.
All in the name of good international relations, right?
Cary