festivals
Karlovacki Dani Piva
end of August
Annual beer festival. The most crowded place at that time of summer, with various folks around. You can grab a beer and pretzel and see if there's a music which suits you.
Mountain Biking
Mountain biking is recommended. Lots of preserved trails all around the city and enthusiastic bikers who'll gladly guide you.
Swimming / Rafting / Kayaking
Great swimming in summer months in Karlovac rivers Korana and near by Mrežnica with rafting and kayaking.