Finland lost access to the Arctic waters as a result of WWII.
However all of our coastal, and internal waters eventually freeze over.
(This year, winter has been mild so far.)
There are two Brigades of amphibious infantry in Finland, the Coastal Brigade, and Nylands Brigade. Both are part of the Navy, rather than a separate organization, like US Marines.
The term “Marine”, in its most classical sense, refers to infantry which travel aboard ships and are specialized in amphibious landings. Unlike the US or UK, Finland only deploys such infantry to defend its own coasts and complex archipelago.
Personnel in the Nylands Brigade have a special right to the title of “Jaeger”, owing to the Brigade’s continuity back from 1626 when it was founded by King Gustavus Adolphus the Great, whilst we where part of the Swedish Kingdom, and are nowadays primarily deployed from the water as a spearhead unit.
The Coastal Brigade primarily deploys from land, to secure the coast from that direction.
In other words, the Coastal Brigade is the anvil, and the Nylands Brigade is the swinging hammer.