Massive erosion over the years on the Ethiopian plateau has created one of the most spectacular landscapes in the world, with jagged mountain peaks, deep valleys and sharp precipices dropping some 1,500 m. The park is home to some extremely rare animals such as the Gelada baboon, the Simien fox and the Walia ibex, a goat found nowhere else in the world.

Simien National Park, in northern Ethiopia is a spectacular landscape, where massive erosion over millions of years has created jagged mountain peaks, deep valleys and sharp precipices dropping some 1,500 m. The park is of global significance for biodiversity conservation because it is home to globally threatened species, including the iconic Walia ibex, a wild mountain goat found nowhere else in the world, the Gelada baboon and the Ethiopian wolf.

The property was established in an area inhabited by humans and, at the time of inscription, 80% of the park was under human use of one form or another. Threats to the integrity of the park include human settlement, cultivation and soil erosion, particularly around the village of Gich; frequent fires in the tree heather forest; and excessive numbers of domestic stock. Agricultural and pastoral activities, including both cultivation of a significant area of the property and grazing of a large population of animals in particular have severely affected the natural values of the property, including the critical habitats of the Walia ibex and Ethiopian wolf. The boundaries of the property include key areas essential for maintaining the scenic values of the property. However, they do not encompass all the areas necessary to maintain and enhance the populations of the Walia ibex and Ethiopian wolf, and a proposal to revise and extend the park boundaries was put forward in the original nomination. Whilst human settlements threaten the integrity of the originally inscribed property, two proposed extensions of the national park (the Masarerya and the Limalimo Wildlife Reserves, and also the Ras Dejen mountain and Silki-Kidis Yared sectors) and their interlinking corridors are free of human settlement and cultivation, and support the key species that are central parts of the Outstanding Universal Value of the property. Several assessments have considered that an extension of the property to match extended boundaries of the National Park, which to include areas with negligible human population are an essential requirement to maintain its Outstanding Universal Value.

The site is located in the western Simen Mountains, 120 km north-east of Gondar in Begemder Province, north-west Ethiopia. With its abundance of creviced basalt rock, Simen serves as an ideal water catchment area, replenished by two wet seasons and the Mayshasha River, which weaves its way north to south through the national park. Consequently the park is rich in a wide range of wildlife and vegetation.

The vegetation is a mixture of afro-alpine woods, heath forest and high montane vegetation. Higher altitudes support montane savannah and montane moor land with tree heath, giant lobelia, yellow primrose, everlastings, lady's mantle and mosses (Grimmiaceae). Lichen drapes the high-altitude forest trees. Ridge tops and gorge sides support coarse grassland with herbs thickets, scattered, and creepers. Forests of St John's wort once flourished at 3,000-3,800 m, but few still remain. There are high, but unquantified, levels of endemism.

The park is home to some extremely rare animals such as the gelada baboon, Ethiopian Wolf and walia ibex, a goat found nowhere else in the world. Walia ibex on the north scarp of the massif are endemic to the Simen Mountains, with most of the population occurring in the park. Simen fox are endemic to Ethiopia, and other mammals include the hamadryas baboon, colobus monkey, leopard, caracal, wild cat, spotted hyena, jackal and several large herbivores, including bushbuck, common duiker and klipspringer. The 400 bird species include lammergeyer, Verreaux's eagle, kestrel, lanner falcon and augur buzzard. A total of 21 mammals have been recorded, with three endemics and 63 bird species, including seven endemics.

The Simen region has been inhabited by human settlers and cultivators for at least 2,000 years. Today it is surrounded by old cultural centres such as Aksum, where over 100 hand-carved stone monoliths (stelae) can be found, Lalibela and Gonder, where curious 15th-century churches and palaces still stand. Erosion indicates that cultivation first started on the gentler slopes of the highland valleys but later extended onto steeper slopes. Simen is at the crossing of old trade routes and records of various local features were made in the 18th and 19th centuries.