The major east-west trending mountain range of the Southern Cape. It extends from Montagu in the west petering out towards the east near Mossel Bay. It forms the boundary between the Agulhas Plain and the Overberg in the south, and the Klein Karoo in the north. Major conservation areas include Marloth Nature Reserve and Grootvadersbosch Nature Reserve.
Four major passes cross the Langeberg: Cogmanskloof Pass lies in the west between Montagu and Ashton; Tradouws Pass links Barrydale with Swellendam; Garcias Pass links Ladismith and Riversdale; and Cloetes Pass links Ladismith with Mossel Bay.
Floristically it is extremely rich with many endemics, particularly it is a hotspot for the Peneaceae. A PhD study was undertaken at the University of Cape Town by botanist David McDonald, who uncovered many rare and new species and wrote a thesis entitled 'Phytogeography, endemism and diversity of the fynbos of the southern Langeberg'.