Passport valid for at least three months beyond length of stay is required by all visitors with the exception of citizens of EU countries who need a valid national ID card.
Nationals of non-EU countries visiting Estonia should be able to justify the reason for their visit as well as have sufficient money for their return journey.
Slovakia is a member of the Schengen Agreement and nationals of the EU and EFTA countries (Iceland, Liechtenstein, Norway, Switzerland) don't need a visa to enter Slovakia for stays of any length.
There are no border controls between countries of the Schengen area. Visitor visas, if required, are valid for all Schengen countries: Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, Malta, Norway, Netherlands, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and Switzerland.
Nationals of the following non-EU/EFTA countries don't need visa to enter Schengen Area for stays of up to 90 days:
Andorra, Antigua and Barbuda, Argentina, Australia, Bahamas, Barbados, Bermuda, Brazil, Brunei, Canada, Chile, Costa Rica, Croatia, El Salvador, Guatemala, Honduras, Hong Kong (SAR), Israel, Japan, Macau (SAR), Macedonia, Malaysia, Mauritius, Mexico, Monaco, Montenegro, New Zealand, Nicaragua, Panama, Paraguay, Saint Kitts and Nevis, San Marino, Serbia, Seychelles, Singapore, South Korea, United States, Uruguay, Vatican City and Venezuela.
Visas must be applied for before leaving for Slovakia at a Slovakian consular office. Note that the 90 day validity period starts from the first country entered in the Schengen Area.