One of the best experiences you can have in life is to watch the northern lights dancing in the skies by the glacier lagoon Jökulsárlón. Just watch this video by Enrique Pacheco and imagine you were there to see them.
Or alternatively, go and experience this for yourself!
If it's just the auroras you're interested in, you can always come to Iceland and book one of Iceland's many Northern Lights tours :)
But we'd recommend going to Jökulsárlón glacier lagoon as well. It is situated in the south east of Iceland, right next to Europe's largest glacier; Vatnajökull. From Reykjavík it takes about 5-6 hours to drive there, so we recommend taking at least 2 days to travel back and forth from Reykjavík.
By driving yourself you choose how long to spend at each location, so we've put together a number of self drive optional itineraries, such as this 3 day winter self drive tour | Ice Cave or this 6 day winter self drive tour | Diamond Beach & Ice Cave.
If you'd rather not drive yourself, then here's a 2 day tour to Jökulsárlón glacier lagoon, that includes glacier hiking as well! If you want to spend longer in the area, you can go on this 3 day tour to Jökulsárlón with ice caving.
The ice caves are only accessible between November and March each year, when the weather is cold. However, you can see the auroras between September and April. For all the best things in winter, check out this 5 day winter package, that includes a tour to the glacier lagoon, the ice caves, the Golden Circle and the Blue Lagoon.
The ice caves are spectacularly beautiful, with their stunning blue ice, so if you are going to Jökulsárlón glacier lagoon in the winter, you should make sure that you go to the ice caves as well. If you rent a car and are planning your own itinerary, you can meet the ice cave guide on location, just join this ice cave tour by Vatnajökull glacier - but be sure to book it well in advance as the tour is popular and sells out!
If you want to know more about the Northern Lights, then here are a few articles about the auroras: Northern Lights (Aurora Borealis) in Iceland, What are the Northern Lights?, Northern Lights in Iceland and Northern Lights Photography.
Have a fantastic time in Iceland!