Northern

Danish, Norwegian, Swedish

These are North Germanic languages, and the speakers of these languages can understand one another.
Danish is spoken by around 5.5 million people; besides in Denmark itself, it is also used by numerous linguistic minorities living in the north-German federal state of Schleswig-Holstein, the Faroe Islands and Greenland. Swedish is spoken by some 10.5 million people, mainly in Sweden and part of Finland, mainly on the coast and on the Åland Islands.
TRANSLATIONS TO AND FROM – Danish

Finnish, Estonian

Finnish is spoken by approximately 5 million people. It tends to be similar to the related Hungarian, although this language, apart from similar sentence construction and vocabulary and morphology, is considerably different. Neighbouring languages that are very similar to Finnish include Estonian, which belongs to the Baltic Finnic branch of the Finno-Ugric languages.
TRANSLATIONS TO AND FROM – Finnish

Lithuanian and Latvian

Baltic languages are of great interest to linguists, as they have retained many of the archaic forms derived from early Indo-European. The Baltic and Slavic branches diverged in around the 10th century B.C. Before that there was not a single unified language, but a number of different dialects.
TRANSLATIONS TO AND FROM – Latvian