Thingvellir National park. This national park is imprtant in an geological sense as well as a historical and cultural sense.
Thingvellir sits in the rift valley that marks the boundary between the North-American and Eurasian tectonic plates. Continental drift is clearly visible here with the plates drifting apart by up to 2cm every year, resulting in a dramatic and unique landscape. A canyon called Almannagjá sits between the plates, allowing visitors to stroll leisurely back and forth between the two continents.