We had the same on the Celebrity cruise this past November. We as Canadian had to go to a special immigration/passport check before we could get off in Key West. They took our passports once we arrive on the ship several days before and advise us we had to attend this immigration/passport procedure to get our passports back or we would never be able to leave the ship in Key West!!! THis wasted about 4 hours of our day as they were late in arriving and the line up to meet the custom people was long. We have no idea why they did this? All non US people had to go thru this procedure. This turn us off a lot as why where we single out. Why not the US people also go thru this procedure?
We can never get an answer.