We start this ride along the River Þjórsá, Iceland’s longest river (143 miles), which is a glacier river in the Þjórsárdalur valley sitting at the foot of the Langmannalauger National Park. Look and listen for the Whooper Swans where the river is close to the road, their distinctive honking call can just about be heard. We cycle over flat lava fields and eventually finish our ride at the Hjálparfoss Waterfall where the rivers Fossá and Þjórsá meet.