The Helsinki Metro system serves the area of Helsinki and southern Espoo. The Helsinki Metro began operation in 1982 and first part of the extension to Espoo was opened in November 2017. The Helsinki Metro is the northernmost metro in the world.
The Helsinki metro consists of two lines (M1, M2) and a total of 25 stations. M1 terminuses are Matinkylä and Vuosaari. M2 terminuses are Tapiola and Mellunmäki. All the stations from Matinkylä to Sörnäinen are underground stations. Stations to east from Sörnäinen are all above ground. Koivusaari station is the only metro station in the world located under the sea.
It's not allowed to enter the platform area without a valid ticket although it's possible to access the platform area without a ticket inspection.