Even before the establishment of the EU one could travel between some of the N. European countries without an immigration check.
The problem with having your passport stamped is that while it may not be a problem for you to visit country B when you later must go to country C it could cause a problem to have a B stamp is your passport.
For example, my wife is of a certain religion and travels to a certain country every year or so.
For the purposes of my work, I have traveled to a certain kingdom that is located in the same general region of that country my wife like to visit.
The word is that if the wrong people in that kingdom were to see that I visited that other country, I could have some issues ranging from being kicked out of the kingdom to having a certain body part that is located in the same general region of my neck chopped off.
keep up the good work
tammy wynnette would be proud
“The word is that if the wrong people in that kingdom were to see that I visited that other country,”
Well, you are referring to the middle east. I have been only to Qatar.
I have not been in any KINGDOMS of Europe other then the UK, haha, but I have lived in Slovakia, Romania, Hungary, and Czech Republic, as well as traveling in Bulgaria and Serbia, and visit my brother in Paris, and other friends
throughout western Europe.
I had no problem crossing boarders with my passport.
I will have to ask my Swedish friends here about northern Europe.