Langjökull is with its 950 square kilometers (after the mighty Vatnajökull) the second largest glacier cap in Iceland.
If you are courageous enough and have a sturdy car, you can try to drive onto the glacier, there is almost a highway.
An interesting thing is that the water in the Þingvallavatn lake origins right from the Langjökull glacier and the melted water reaches the lake under the ground.
How to find Langjökull:
From the road F550, there is about 7 kilometers long unpaved road leading to Langjökull.
GPS coordinates of Langjökull: 64.642596, -20.557089 Take me there!
Photos of the Langjökull glacier:
The Nearest Glaciers