At 3,011 metres, Pico Basile is taller than the highest peak in Spain and not far below the height of Mont Blanc, Europe's tallest mountain. Climbing it is a real adventure because the forest changes as you go up: at the bottom are tall trees with thick canopies, higher up the trees get shorter and twisted by the wind, and near the top you walk through open grassland dotted with giant lobelias - unusual plants that look like something out of a fairy tale.
The volcano is old enough that it has not erupted in recorded human history. Scientists classify it as dormant, which means it is asleep rather than truly extinct. The whole mountain is protected as part of a national park, and the forest that covers it is home to drills, Bioko forest monkeys, and many rare birds.
Because Pico Basile rises so steeply from the warm sea, it captures a huge amount of rain from passing clouds. The eastern slopes are particularly wet - some parts receive more than nine metres of rain each year. That is more rain than falls in four years in London! All that moisture keeps the forest green and lush every single month.
On very clear mornings, before the clouds build up, hikers at the top can look across the water and see the enormous silhouette of Mount Cameroon rising to 4,040 metres on the other side. The two volcanoes face each other across the sea like friendly giants.