Kesänkijärvi is a small lake sandwiched between two fells and this is why it's so incredibly beautiful! Lake views with fells in the background, what could be better. You can drive next to the lake and park your car there. There's a small path that takes you straight to the edge of the water and a small jetty, this is a super nice spot for photos. Or then you can continue walking the other path into the forest and go do some exploring! You will find awesome places on the way and if you keep walking long enough, you will come to a small fireplace. If you walk even more, you will find a cafe called kesängin keidas! ;)
You can also make a longer trip by hiking the "Pirunkuru" up to the top of Kesänkitunturi, which is a really nice hike with awesome views.
If you want a shorter trip, then just walk around the lake.
Look out for the local birds "Siberian Jays" which will come and eat snacks from your hand!
I love this place a lot.