Hengifoss at 118 m in height is the third highest waterfall in Iceland and is on the west shore of Lagarfljot, near the southern tip of the lake.
From the car park, there’s a trail to the waterfall, a return hike of 1.5 hours (2.5km each way).
The path climbs about 300m on a rather steep gravel trail but it is worth the effort.
From the viewpoint over the waterfall and its gorge you’ll see colorful bands exposed in the rock face, formed when a layer of volcanic ash covered a basalt lava flow.
The mineral-rich ash became soil and clay compounds were formed. Then iron-rich lava flowed over the soil causing it to oxidize and turn red, resulting in the reddish clay trapped between the thicker basalt layers.
Litlanesfoss is another waterfall further downstream, made all the more spectacular as it is framed by basalt columns.
In winter snow and ice may make this walk hazardous.