Bukit Lawang, North Sumatra, Indonesia, was once the site of an orangutan rehabilitation project, and continues to provide an opportunity to view both semi-wild and wild orangutans on daily excursions into the Gunung Leuser National Park. It is forbidden to touch, feed, or disturb them, yet such practices still do occur. This is a major cause for concern in terms of disease transfer due to the close relationship between humans and orangutans. Unauthorized food provisioning also discourages the semi-wild population from reducing any dependence on humans and becoming free-living in the wild. There are wild orangutans within the area, and there is regular interaction between the two populations. We are implementing new protocols and sustainable ecotourism standards, such as minimum distances from the animals, limited group sizes and viewing times, in accordance with new IUCN guidelines. These will help sustain the remaining orangutan population in the area, reduce any negative effects of tourism on natural behaviour and prevent disease transmission between orangutans and humans. We are hosting an extensive training program for the existing, but poorly trained, guide association, covering issues such as the concepts of conservation, ecotourism and forest ecology, fauna and flora, lessons on conducting environmental education, as well as methods of maximising visitors' experiences, first aid training, forest survival and navigation skills. It costs £6,000 to train 30 guides and provide uniforms and teaching resources. We have already trained 90, and there are 60 guides remaining, waiting to go through our programme. Park guides are in a unique position to serve as ambassadors to a countless number of national and international visitors to the Gunung Leuser National Park, so it is vital that they are well-trained and informed. The training sessions will make conservation issues explicitly relevant to the forest guides, who rely on the rainforest ecosystem for their income, and make them aware of their role and responsibilities in maintaining the sustainability of the Gunung Leuser National Park. The programme will contribute to strengthening the guide association's capacity to monitor and enforce good practice and forest guidelines, ensuring a more secure future for the local community, a more valuable experience for visitors, and far greater potential for the orangutan population in the area to thrive. Such improved enforcement of guidelines will help ensure the health and safety of the orangutans and other wildlife in the park (as well as the visitors themselves), whilst adding to local community knowledge through the capacity building nature of the training. Thereafter they will be better able to serve the tourism industry, resulting in visitors becoming more informed themselves on the orangutan conservation situation, as well as that of rainforests in general. All of these outcomes will strengthen local efforts to help biodiversity and ecosystems co-exist with human development.