Capture Iceland's stunning Aurora Borealis against the Grotta Lighthouse.
While I was in Iceland for 10 days, I was blessed enough to see the northern lights every single night. Because of all the opportunities, I was able to learn some lessons about them.
The best times to see the northern lights in Iceland are late fall, early winter, or early spring. It will only get dark enough to see them in the winter whereas during the summer it never really gets dark at all so they aren't visible. Mid winter does get dark enough but it will most likely be cloudy and rainy, which is why it is best to go when the weather is transitioning into winter so you get the darkness without the storms. It also doesn't have to be late at night either. I saw them as early as 7:30 PM so as soon as it gets dark have your gear set up and be aimed for the sky.
While out in the day, look for open areas without tall trees or objects blocking too much of the sky. Plan out where you will try to shoot them ahead of time so you are ready and don't have to scramble around when they come out. Some epic places to shoot them are Seljalandsfoss, Jokulsarlon, and Kirkjufellfoss if you are out of ideas. If you are stuck in Reykjavik, you can always walk down to the lighthouse and shoot them there, it is just about an hour and a half walk from the center of town.
Before going to Iceland, I would recommend getting your night photography down. Shooting the Aurora is similar to shooting stars except that you actually will want to keep your exposures a bit shorter so they keep their forms and don't just look like big green blobs. They slither around pretty fast and are constantly changing direction. Use aperture and ISO as your priority for brightness but don't open up anymore than 2.8 so you can still keep everything fairly narrow and in focus, but it's up to you as well. If you aren't sure where to begin, I would start with your aperture at f/2.8, your shutter at 5" and your ISO at 1600. From here play around with your settings and try lengthening your exposures and lowering your ISO or visa versa. They really are bright so you don't need to bump your settings up too high. If you are shooting timelapse, you will probably want to keep your intervals short so that the streaks of light don't move too quickly when you play it back, but again, depends on what you want.
Like I said, the key to getting awesome shots of the Aurora is to be ready for them. If the skies are clear, you are most likely going to get a good show!