provided by Entry and Customs in Sweden
A valid passport is always required when entering Sweden. Us citizens are allowed 90 days in Sweden without a visa, and don’t be surprised if you’re actually tempted to stay that long! The 90 days begins when you enter any of the Schengen countries, which includes: Austria, Belgium, The Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, and Sweden. Not all borders are staffed with officials to stamp your passport, so if you need proof of entry into Sweden, you might have to get one at an official point of entry. Don’t be surprised if you’re asked questions about your visit to Sweden while your passport is stamped. This is standard procedure. Just tell them you’ve planned an amazing trip in what is one of the most unique countries in the whole world!
U.S.A, Canada, U.K, Australia, New Zealand have there own custom laws with Ireland.