The Colombian Amazon is a world of layers. At the very top, the tallest trees poke up above everything else - these are the 'emergent' trees, and eagles nest up here in the sunshine. Below them is a dense roof of leaves called the 'canopy', where monkeys, toucans and sloths spend most of their lives. Below that is the 'understory', dim and cool, home to frogs, snakes and insects. On the forest floor it is darker still.
Walking through the Amazon feels like being inside a living building. Roots twist out of the ground like giant fingers. Giant lily pads float on the surface of slow brown rivers. Butterflies the size of your hand flutter between shafts of light. The air smells of mud, flowers and rain all at the same time.
The Amazon river itself is extraordinary. It carries more water than any other river in the world - about one fifth of all the fresh water on Earth that flows into the sea. In the rainy season, the river spreads so wide that parts of the forest flood - and fish swim between the trees.
Many Indigenous communities have lived in the Colombian Amazon for thousands of years. They know the plants, animals and rivers better than anyone. Some plants that doctors use today were first discovered by these communities, who shared their knowledge with scientists.