My favorite place for Northern lights (Aurora Borealis) photography is Jökulsárlón, the glacier lagoon. The lagoon offers a great combination of background, foreground, and merely all ingredients for a good photo. On a calm day, the lagoon, the water, adds a lot to the image as the lake's northern lights reflect, often creating incredible photos.

September evening as Aurora Borealis lights up the sky and reflects in the lagoon

Jökulsárlón lagoon is a great place to take photos of the northern lights