You do not need to show a Passport if: "You are an EU citizen traveling within border-free Schengen EU countries. These countries are: Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and Switzerland. However… you should still carry your national ID card or passport for shopping, in case of emergency, or in case travel regulations change."
You need a passport if: "You are not an EU citizen. Passports must be valid at least 3 months beyond your departure date, and have a full page for your entry stamp."
You can typically apply for a passport at your local Passport Office. Depending on your country of citizenship, you can renew your passport, even if it has not yet expired, by mail or online.
"You need a valid Passport or ID card if:"
"You are an EU citizen traveling from the other EU countries: Bulgaria, Croatia, Cyprus, Ireland, Romania or the UK. Children and infants also need a valid ID card or passport. Your passport must be valid for the entire duration of your stay."
You don’t need a Visa if: "Are staying for less than 90 days, and are a citizen of the EU, or one of the following countries: Andorra, Argentina, Australia, Brazil, Brunei, Canada, Chile, Costa Rica, Croatia, El Salvadore, Guatemala, Honduras, Israel, Japan, Malaysia, Mexico, Monaco, New Zealand, Vatican, Nicaragua, Panama, Paraguay, Saint Marino, South Korea, USA, Uruguay or Venezuela. However…if you are an EU citizen, you still need to bring your European Health Card (EHIC) or your county's Social Security service documents."
You need a Tourist Visa if: "Are not a citizen of the EU or one of the above countries. Travel insurance may also also something you'll need to get into Iceland."
"You do not need any vaccines unless:You are coming from a yellow fever affected region, such as a tropical or subtropical area of South America or Africa, then you'll likely need proof of a yellow fever vaccination. However…You should always be up-to-date on routine vaccinations when traveling."