"Finland is cold, so The Chocolate Factory also gets to trumpet the green credentials of the location because the DC is cooled using Gulf of Finland seawater to ameliorate the heat made by its servers, [...]"
It is cold in winter - but summers can be hot with the long days. The Gulf of Finland is part of the Baltic Sea. They are both relatively shallow and less salty - owing to inflowing rivers and the constricted connection to the North Sea through the Danish Straits.
While the Baltic freezes in winter - in summer it warms up nicely. Living in a summer cottage on the coast near Stockholm my bath nights were in the Baltic. You could buy a special soap that would lather in that brackish water. Near the end of October the water started to get colder - and felt more like an English coastal sea summer temperature.