At the Tourist Office, you can purchase tickets for guided tours of the city, lasting 2 hours and taking in the highlights. Departure is from Torvet or Market Square daily at 11am between May 22 and August 27. Adults pay 185NOK ($28/£15), while children under 16 enter free if they're accompanied by an adult.
The tourist office publicizes a 1 1/2-hour sea tour, going along the canal harbor and up the River Nidelven and out to the fjord. From June 23 to August 18, it leaves Tuesday to Sunday at 2pm, costing 140NOK ($22/£12) for adults and 45NOK ($6.95/£3.70) for ages 3 to 14. From July 3 to August 4, there is an additional departure at 4pm, and from August 21 to September 8, there are tours on Wednesday, Friday, and Sunday at 2pm.
The tourist office can also recommend an evening boat tour, lasting 1 1/2 hours, departing every night between June 30 and August 4 at 6pm from the Ravnkloa market. The cost is 140NOK ($22/£12) for adults and 55NOK ($8.45/£4.50) for children ages 3 to 14. For this and the sea tour above, buy your tickets directly on the boat.