A view over Bukit Tigapuluh NP at sunrise, Sumatra, Indonesia. © Daniel Rosengren

Getting to Bukit Tigapuluh involved lots and lots of mud, getting stuck in it, digging and winching ourselves out, multiple times. © Daniel Rosengren

The sunlit leaf of a fern. © Daniel Rosengren

The Flying Frog can't actually fly, but can indeed glide quite well using the webbing between their toes. © Daniel Rosengren

A young Orang-utan enjoying freedom in the jungle. © Daniel Rosengren

A young Orang-utans drinking water. © Daniel Rosengren

The hand of an orang-utan learning to survive in the wild. © Daniel Rosengren

The cheekiest student in jungle school, Suro, always looking for mischief. © Daniel Rosengren

A young Orang-utan climbing on thin branches. © Daniel Rosengren

A young Orang-utan out on a limb, her trainer is seen below. © Daniel Rosengren

A Orang-utan enjoying sitting in a Strangler fig. © Daniel Rosengren

A Sumatran Orang-utan climbing in the forests of Bukit Tigapuluh. © Daniel Rosengren

A Sumatran Orang-utan in a strangler fig. © Daniel Rosengren

A strangler fig is a great play-ground for a young Orang-utan. © Daniel Rosengren

An Orang-utan in a palm tree on Sumatra. © Daniel Rosengren

An Orang-utan in Bukit Tigapuluh, Sumatra. © Daniel Rosengren

The sun is making the hairs of this Orang-utan to glow. © Daniel Rosengren

A young Orang-utan using a liana as a hammock, chillin'. © Daniel Rosengren

This huge male, Win Gayo, was once a jungle school student and is now one of many successfully re-introduced Orang-utans in Bukit tigapuluh. © Daniel Rosengren

A young orangutan (Kedaung) carried out by trainer Siti Fatimazzahra to jungle school. Before being released, orangutans need to learn several skills so they can survive better. © Daniel Rosengren

The rainforests of Bukit Tigapuluh, Sumatra. © Daniel Rosengren

The Sumatran Elephant is the smallest sub-species of the Asian Elephant and is Critically Endangered. © Daniel Rosengren