Lake Peipus is the largest trans-boundary lake in Europe, lying on the international border between Estonia and Russia.

Estonia, officially the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, and to the east by Lake Peipus and Russia. The territory of Estonia consists of the mainland, the larger islands of Saaremaa and Hiiumaa, and over 2,300 other islands and islets on the eastern coast of the Baltic Sea, covering a total area of 45,335 square kilometres (17,504 sq mi). Tallinn, the capital city, and Tartu are the two largest urban areas of the country. Estonian, a Uralic language, is the indigenous and official language of Estonia, and it is the first language of the majority of its population of 1.3 million.