Sysendammen is one of Norway's largest rockfill dams - over a kilometre long, 81 metres high, built from 3.6 million cubic metres of stone and moraine. It took six years to construct, completed in 1980.
The dam holds back Lake Sysenvatnet, the main reservoir for Sima power station - Norway's second largest, hidden 700 metres inside the mountain down at the fjord. A 22-kilometre tunnel system connects them.
The dam also controls flow to Vøringsfossen - there's a legal minimum so the waterfall keeps running in summer. On clear days you can see Hardangerjøkulen glacier to the north.