Sambar deer
The park consists mainly of mountains and hills, with elevations ranging between 336 and 2257 metres. The area is the source of many rivers. It is named after the Nam Et River and Phou Louey Mountain ('Forever Mountain'). The area has a high level of biodiversity and endangered species including tiger, leopard, clouded leopard, Asian golden cat, marbled cat, civet, gaur, Sambar deer, white-cheeked gibbon, sun bear, black bear, Asian elephant, dhole, hornbill and three species of otter. As from 2013 on there is no proof of tigers in the park anymore which makes them extinct in entire Laos. Leopards vanished from the park even earlier.