Other non-EU countries however can join the Schengen agreement and thereby make it possible to travel between the Schengen countries without showing passport.

The Schengen Agreement make it possible for citizens from outside "Schengenland" to apply for only one Schengen Visa when visiting several countries in Europe - instead of applying for visa in an embassy of each of the countries you want to visit.

Countries that take full part in the Schengen Agreement and therefore can be visited with only one visa are:

Countries that are not full members of the Schengen Agreement and to which it is not possible to travel without showing passport / visa:

The new EU countries  Bulgaria, Cyprus and Romania are - as all new EU member states - bounded to be part of the Schengen Agreement. Therefore it is only a matter of time when the will be part of the passport free Schengen zone.

At 12. december 2008 Switzerland joined ot be full member of the Schengen agreement and now be visited with a Schengen-visa and without showing passport. For a period though there will still be passport control in the airports. 

The EU countries Great Britain and Ireland have reservations in relation to the passport free zone which means that Schengen Visas and still cannot be used when entering these countries and Schengen citizens must show passport at the border. In near future there is no change that this will change. The two countries Howe ever are part of the Schengen information system SIS and SIRENE.

Greenland and Faroe Islands are part of the Danish kingdom, but they are not member of the EU and not member of the Schengen Agreement either. However they do have an agreement with the EU to ensure that EU citizens can travel also in Greenland and the Faroe Islands without showing passport at the border. But do note: A Schengen Visa  - even to Denmark - does not automatically give permission to visit Greenland and the Faroe Islands.

In other cases one Schengen Visa is enough, even when you visit several Schengen Countries. You might though have to tell the consulate in advance which countries you want to visit. In most countries you also need to register to the national authorities if you are making private visits longer than 3 days.

In the Schengen area there is normally no passport control but anytime of the countries can re-establish passport control if needed for security reasons. It has been done close to international summits or other critical events. So if you are unlucky you might need to show your passport at a border after all.

Also not that when travelling in the Schengen countries you always have to be able to identify yourself. Which means: You have to bring your passport anyway!

This site is a privately owned information page about travelling in the Schengen Land. If you need more information about Schengen try:

Information about Schengen from The Danish immigration Service

The European Commissions site about travelling in Europe

Description of the Schengen Agreement on Wikipedia