There is actually a real ice-cream parlour in the city! One of the very few things I missed from my home country was the occasional ice-cream-cone on a hot summer day. You can find ice-cream in Helsinki of course, but this is actual home-made ice-cream, and the scoops are the hugest ones I’ve ever seen (it limits the amount of flavors you can taste at once though, a bit of a shame)!
They have a couple of locations in the city, but the one that makes your day is on Merisatamanranta. Take a walk from Kaivopuisto along the sea and the beautiful sailboat harbour, get yourself a massive amount of ice-cream, sit at the ocean and enjoy the sun.
They have a decent selection of flavors, but it’s actually so popular that they often sell out some by the end of the day!