1. Go to a lake. Flaten or Källtorpssjön.
2. Try a Cinnamon bun. (or Kanelbulle in Swedish)
3. Try Swedish meatballs with lingonberries.
4. Go thrift shopping in Södermalm. Go to Myrorna, the cheapest thrift store in Stockholm.
5. Have a picnic in the park in Södermalm.
6. Have drinks while watching the sunset in Norrmalm.
7. Walk through old town and go to one of the cute cafes.
8. Take a ferry boat over to Djurgården island from Slussen and go to a museum or the theme park, Gröna Lund. The Vasa Museum has a sunken ship they brought up to land. Or go to the Abba museum.
9. Stay at a hostel on a boat. There is a nice one called Rygedjord. You can find it on hostelworld.
10. Try a Swedish Ice Cream.
BONUS-Go to Esa Sushi!