In almost every town in Finland you'll find a local tourist office or bureau. Usually keeping normal office hours, these bureaus provide free brochures and maps of the town or region, and details on all the best attractions.
Most of them also handle reservations for accommodation, and sell tickets for events and happenings, boat cruises. If there are local guides or guided tours, they will also have information on these too, as well as details on restaurants, bars and nightclubs.
Discovering Finland have provided contact information and map locations for local and regional tourist offices, including the many that operate as part of National Parks. You'll find them by choosing 'Listings' from the main menu, then clicking 'Getting Around' and 'Tourist Information'.