Helderberg Nature Reserve, nestled above the Somerset West area on the slopes of the Hottentots Holland Mountains, was proclaimed on the 23 September 1960. It was initially proclaimed as a wildflower garden and to protect water resources for Somerset West. Today the 402 hectare reserve supports the protection of critically endangered Swartland shale renosterveld and Kogelberg sandstone fynbos, as well as the vulnerable Cape Winelands shale fynbos, and pockets of the least threatened Southern Afro-temperate Forest. The reserve is home to 613 plant species, 13 of which are threatened with extinction. In the deep, more fertile granite soils, species such as the waboom (Protea nitida), and the green sugarbush (Protea coronate) form a fairly dense, closed shrubland. In wetter areas, restios and a variety of ericas and watsonias, as well as other shrubs are found. Helderberg Nature Reserve has a confirmed bird list of over 170 species which includes all seven of the fynbos endemics. A mammal list comprising 42 species has also been recorded. The Cape leopard (Panthera pardus) has been sighted on the slopes within the reserve, as well as the striped weasel (Poecilogale albinucha), honey badger (Mellivora capensis) and the recently re-introduced grey rheebok (Pelea capreolus). Smaller mammals such as grey duiker (Sylvicapra grimmia) and Cape hare (Lepus capansis) are often seen within the well maintained picnic sites.
30 reptile and eight amphibian species have been recorded in the reserve, of which the leopard tortoise (Stigmochelys pardalis), although not locally indigenous to the area, is the most commonly spotted. Amphibians such as the clicking stream frog (Strongylopus grayii) and De Villiers moss frog (Arthroleptella velliersi) can be heard from the many streams and pools in the area.