Some flag facts about the flag of Finland:

The flag of Finland features a blue Nordic cross on white background, the cross representing Christianity
The flag is also called siniristilippu or ‘Blue Cross Flag’
The flag was adopted after independence from Russia
The design of the flag can be traced back to the Russian Navy ensign
The blue color also represents Finland’s many lakes and the sky, the white represents the snow covered landscape in winter
It is a custom in Finland to fly the flag at Midsummer from 6 pm of Midsummer eve until 9 pm of Midsummer’s day to symbolize the lack of darkness in any part of Finland during Midsummer’s night
Officially adopted in 1918