Unfortunately, Helsinki doesn't have the same Mummy Troll Valley as Naantali, but there's still plenty to keep the kids entertained:
Linnanmäki Amusement Park has plenty of rides to suit all tastes (the most popular is the "Mad Stream" inflatable boat ride), and you can climb a tall observation tower with a rotating platform. And in winter, you can visit Santa himself!
Helsinki Zoo is a huge green oasis on the island of Korkesaari. Lynx and leopards, Ussuri tigers, bison, wild goats - all these animals visitors can not only see, but also smell! Yes, yes, the creators have provided an original entertainment: by pressing a button on a special machine, you can find out how a skunk smells, for example.
Squirrel Island (Seurasaari) is a favorite entertainment place for children in Helsinki, and Finns come here as a family. Here you can not only see Finland's national dwellings, brought here from all over the country, but also feed the squirrels with nuts.