Kouga, the larger and more extensive of the two ranges, contains many high peaks in its central and western sections, of which Smutsberg is the highest at 1 757 m a.s.l. At its eastern end, the range is less rugged consisting of plateaus and rolling hills below 900 m a.s.l. Relative to Kouga, the linear Baviaanskloof range is far narrower and much more uniform in shape, with Scholtzberg (1 625 m a.s.l.) as its highest peak. The north-facing slopes drop steeply to the Great Karoo.

Three main rivers drain the area: the Baviaans and Kouga rivers flow eastward into the Kouga Dam, while the Groot River flows through a spectacular gorge before joining the Gamtoos River, which runs to the coast. Quartz sandstone sediments of the Table Mountain Group dominate the area. To the north, the fynbos-covered sandstone gives way to sandstone slopes of arid fynbos, which in turn make contact with the Bokkeveld Shales of the Great Karoo plains. The temperature regime in these mountains is temperate, ranging from an annual average minimum of 5 °C to a maximum of 32 °C. Rain can fall at any time of year, brought mostly by cut-off lows. These systems are slow-moving pockets of cold air from the mid-latitude South Atlantic Ocean that are trapped in the south and east of the country by high-pressure cells. In the lower-lying areas (<350 m a.s.l.) rainfall averages less than 250 mm p.a., whereas the high-altitude areas (>800 m a.s.l.) generally receive more than 800 mm p.a. In the west there is no marked seasonal pattern; in the east rainfall tends to be higher in summer. The local topography has a dramatic influence on rainfall events.

The mainly leached and acid soils, derived from sandstones and quartzites of the Table Mountain Group, support mesic mountain fynbos dominated by a multitude of communities, although fynbos species are foremost among these. Afro-temperate forest patches dominated by trees are found in deep, secluded, mesic gorges. Arid veld occurs on the xeric northern slopes. Spekboomveld is found on the steepest slopes at the lowest altitudes, primarily due to grazing pressure on more gentle slopes, and is dominated by spekboom and other succulents. On the plains of the Great Karoo, karroid scrub appears. Local patches of renosterbos are found on the higher hills and ridges.

The Kouga–Baviaanskloof Complex, together with the surrounding plains, supports a remarkable number of avian habitats, making it home to approximately 300 bird species. All the Cape Fynbos restricted-range and biome-restricted assemblage species are found in the mountain ranges. Several South African Forest restricted-range species occur in the forest patches, and the Great Karoo plains in the northern foothills support several Namib-Karoo biome-restricted assemblage species. Several days are recommended to explore the area in sufficient detail.

Key species:

Knysna Woodpecker, Knysna Turaco, African Firefinch, Tambourine Dove