My favorite park for picnic in Helsinki is Park Sinebrychoff (also known as Park Koff, in Finnish Koffin puisto). Maybe it is my favorite since I live near by – however for sure it is very popular park for picnic or just sitting and enjoying summer among locals. Situation is great, near to see in the end of Bulevardi, so easy to walk there but also tram 6 passes by. Also city bike station is very close by. Exact address for park is Sinebrychoffinkatu. Park is quite big so you can always find a spot for you and your picnic blanket. Need something to bite? Then head for big grocery store S-Market near by (I wrote about this grocery store before). You can also find restaurant South Park in the park if you aren’t up for picnic and want to have a proper table instead.
For art lovers I recommend Sinebrychoff Art Museum which is in the park (the address is Bulevardi 40) and seen above picture (yellowish old building).
There is great playground for kids nearby – just walk the hill up and continue maybe 300 meters and you see the playground (ask somebody if you don’t find it).
And then – sometimes it starts to rain just when you are enjoying your day at park. That happened me last Thursday. When I realized rain is definitely coming I collected all my stuff and run to Hietalahti Markethall (Hietalahden halli). There is this great historical feeling of markethalls – you can feel there have been selling and buying for many, many years before you have been born. You can buy lunch, best milkshakes in town as well as meet, vegetables and souvenirs. Markethall is not open in the evenings (except Saturday and Sunday, opening hours below) – it is more place for lunch and ice-cream. So great place I recommend you to pay a visit there even not raining! In front of Hietalahti Markethall there is great flea market to wonder around – recommend that as well!