Oulanka National Park is in Finnish Lapland near Kuusamo. The first thing I have to say is that if you decide to make the 80km long route it would be much better in summer since in mid-October it was very snowy and the thermometer reached 15 degrees below zero. Crazy! Especially when all you are the houses that have no hot water. You can choose to camp and die too! Hahaha. No, seriously summer's best in addition to carrying less in your backpack and being able to bathe in the river (though it is surely too cold). Also in Autumn the days are quite short and in winter there are no more than 4 hours of daylight (which are still dark), and you have no time to get from booth to booth.