Nuuksio in January, on foot
Nuuksio is the national park most people from Helsinki know, and in summer the main trails are busy. In January, on a weekday, I met four people in five hours. The bus to Haltia runs often enough, and from there it is a walk along the road to Haukkalampi where the marked loops start.
I took the Korpinkierros loop, about seven kilometres, which follows a ridge and then drops into bogs and small lakes. After a week of snowfall the trail was packed only near the start. Past the first lean-to I put on snowshoes and kept them on until the end.
Fire and lean-tos
The lean-to at Mustalampi had dry wood in the shed, which is not always the case in winter. I made coffee, ate a rye sandwich and sat for half an hour watching the light go orange around two o'clock. By half past three it was getting dark under the trees.
What I would change
I would start earlier. Winter days here are short, and the last kilometre in the forest with a headlamp was slower than expected. I would also bring a second pair of gloves; the first got wet from brushing snow off the bench.