The largest wilderness area in all of Southeast Asia lies in the north of Sumatra, a region whose ancient forest and extraordinary biodiversity are being eroded at an unnerving speed by the spread of palm oil production and logging. Of particular importance is the primary jungle covering the mountains of the Gunung Leuser National Park (GLNP), a stronghold of the Sumatran tiger, Sumatran rhinoceros, Asian elephant and orangutan.

While sightings of the first two species are extremely rare these days, you’re guaranteed a glimpse of an orangutan at the famous Bohorok Orangutan Centre at Bukit Lawang. Set up by a pair of Swiss naturalists in the 1970s to care for and train rescued animals for release into the wild, it is now run as an ecotourism site and centre for conservation, learning and education. Accommodation is in simple, but clean and spacious ecolodges set in lush forest, where the accent is very much on experiencing nature rather than high luxury.