Geologists call Voltzberg an 'inselberg', which is a German word meaning 'island mountain'. These rounded domes form when a hard lump of rock survives millions of years of erosion while the softer rock around it wears away. Voltzberg's rock is some of the oldest on the planet — it is thought to be around 1.7 billion years old.
The climb to the top takes a few hours through the rainforest, and then suddenly the trees give way and you are scrambling up bare, warm rock. Harpy eagles nest near the summit, and hikers sometimes spot them soaring overhead with their huge wingspan of nearly 2 metres. The view from the top is one of the most spectacular sights in all of South America.
Voltzberg sits inside Raleighvallen Nature Reserve, named after the English explorer Sir Walter Raleigh who searched this area for the legendary city of gold. No city of gold was ever found, but explorers today find something even better — miles of untouched jungle teeming with life.