colinla

did you have a non-Schengen port on your Oceania cruise?

I suspect yes and that is why you had disembarkation customs, which took 20 minutes.

Traveling on the Koningsdam, Amsterdam to some Norway ports and back to Amsterdam. Upon arrival back in Amsterdam at 7AM, will the boat and passengers have to go through any customs, immigrations, or border controls?

Both the Netherlands and Norway are Schengen.

Perhaps Dutch authorities consider the ship to have been in international waters and thus require international border procedures?

Trying to decide how aggressive I will be on the flight timing home.