I hope you will have a car while you are here in Tromso. If you want fjords and wild mountain landscapes, then the island Senja, about 3 hours drive from Tromso, is spectacular. Especially the outer parts like Husoy, Mefjord, Gryllefjord.
An alternative closer to Tromso are the islands Kvaloya and Ringvassoy - these are the places I travel to for shooting northern lights. Plenty of fjords and mountains, an hour drive from the city. But there are not many great waterfalls around here.
The mountain range called the Lyngen alps are also a great place for landscape photography, and spectacular when the northern lights explodes over them!
Remember that after the 25th November you don't see the sun for the next two months, but during that period the (lack of) light can be very beautiful.