Although they are not technically part of the Schengen area, the micro-states of Monaco, San Marino and Vatican City have open borders with the Schengen countries that surround them, making them accessible to travelers had Schengen visas (although these countries cannot issue the visas themselves). Participating countries are required to strictly control travellers entering and leaving the Schengen area. These controls are coordinated by the Frontex Agency of the European Union and are subject to common rules. The details of border controls, surveillance and the conditions under which authorisation to enter the Schengen area may be granted are conclusively defined in the Schengen Borders Code.   Andorra is inland and has no airport or seaport, but there are several heliports. Visitors to the country are only accessible by road or helicopter via Schengen members France or Spain. Andorra maintains border controls with France and Spain. There are also border controls in the other direction, but these are more focused on customs control (Andorra is considered a tax haven with 4% VAT). Andorra has no visa requirement. Citizens of EU countries need an identity card or passport to enter Andorra, while everyone else needs a passport or equivalent passport.
Schengen visas are accepted, but travelers who need a visa to enter the Schengen area will need a multiple-entry visa to Andorra, as meant by entering Andorra and re-entering France or Spain is considered a new entry into the Schengen area. Andorran citizens do not receive a passport stamp when entering and leaving the Schengen area.  For stays throughout the Schengen area of more than 90 days, a third-country national must hold either a long-stay visa for a maximum period of one year or a residence permit for longer periods. A long-stay visa is a national visa, but it is issued according to a uniform format. It authorises its holder to enter the Schengen area and remain in the issuing State for a period of more than 90 days, but not more than one year. If a Schengen State wishes to allow the holder of a long-stay visa to stay there for more than one year, the State must issue him a residence permit. In response to the European migrant crisis in 2015, several Schengen countries have implemented border controls. Lithuania is known to have the highest acceptance rate. In 2018, up to 98.7% of Schengen visa applications for Lithuania were approved. Other countries with high adoption rates are Estonia, Finland and Iceland. .