Gjáin in Thjorsardalur valley is a pair of falls within a lush garden paradise nestled within a rift zone. While the waterfalls themselves are attractive, the rift zone setting is really beautiful in that it feels like you are entering a different place that contrasted from the typically dry and desolate desert highlands surrounding the area.
This is a lava area and the lava can take on such beautiful form. There are several lava caves in Gjáin and all over there is columnar basalt and volcanic tuff.