Trölladyngja is Iceland's largest shield volcano, located in the north of Vatnajökull National Park in the highlands.
Explore this area on a self drive tour in Iceland.
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At 1,468 metres (4,816 feet) tall, it is the tenth largest mountain in the country; it rises about 600 metres (1969 feet) from the surrounding Ódáðahraun lava fields and desert. Its diameter is even more impressive, as it is 10 kilometres wide. It has an oblong crater that is 1,500 metres (4921 feet) at its widest, and 100 metres (328 feet) deep.
Trölladyngja is still active, last erupting in 1961. Earthquakes around it are monitored closely.
Shield volcanoes are formed by highly fluid lava with low viscosity pouring from a crater in all directions, travelling far before solidifying, and giving the peaks their distinctively gentle slopes.