You can walk to most attractions in Helsinki. And since transportation is expensive (3 euros per ride or 8 euros for a day pass or 12 euros for 2-day pass), it’s good to know that you can walk to most places.
Day 1
Morning
Get out from the ferry, walk to see Uspenski Cathedral. And Helsinki Cathedral.
Free Attraction- 4 Unique Churches in Helsinki
Afternoon
Relax at Espandi park and check out market square. Go to a sauna. Or if you feel like taking a walk or you don’t mind paying 3 euros for a bus ride, you can go swimming at Hietaniemi Park.
Evening
I didn’t have an evening in Helsinki, but I suppose you could go to Sibelius Park (near the Rock church)
Day 2
Morning
Visit Suomenlinna! (Get a day pass for 8 euros)
Free and Worthwhile Attraction: Suomenlinna the Castle of Finland
Afternoon
Then go to Rock Church. If you have time, stop at Kamppi for chapel of silence.
Then leave!
Final Word
If you have an extra day, you can also go to Nuuksio National Park or Seurasaari (open air museum). For me personally there isn’t that much to see Helsinki. But I’d still like to see Nuuksio National Park next time!