Let us first define the chess board. The given coordinates point to water in Eteläsatama and they define square h4. In addition square c8 is at N60°10,844' E24°56,054'. I.e. squares aren't actual squares, but points.
Assume that earth is flat i.e. distance between squares does not get smaller when you travel northwards. However, you should note that distance between two squares in north-south direction is different from that of in east-west direction. The board is placed so that white plays directly from south to north.
The pieces are set on board as follows.
WHITE: Ka7, Qg7, Ra4, Rh6, Ne1, Nc4, Bc7, Be8, e4
BLACK: Kc5, Qg1, Rb3, Rf5, Na1, Nd5, Bf8, Bg8, d3, b7
White moves first and will checkmate in second move, disregarding what is black's response to the first move. Your task is to find what is white's first move. The cache is in the square to where white will take his piece in that move.
No dangerous activities are necessary, but keep an eye on geomuggles. Cache remains accessible disregarding the amount of snow, but to reach it you may need to do some snow clearing.
Update 1 Oct, 2017: Due to advancements is positioning technology over the past decade, it is now possible to measure cache location more accurately. I'm not going to modify description; Just make the following correction to your finals coords: N -0,004' and E -0,003'