The Harold Porter National Botanical Garden covers almost 200 ha between mountain and sea, in the heart of the Cape Fynbos region within the Kogelberg Biosphere Reserve to the east of Cape Town, South Africa, specifically near Betty's Bay along Clarence Drive (R44).

Foot trails reach cliffs, ravines, heaths, forests, streams, and mountain pools.

In 1939, Harold Nixon Porter, Jack Clarence, and Arthur Youldon, purchased the land between Rooi-Els and the Palmiet River.

After Porter's death, the land was passed to the South African National Biodiversity Institute (SANBI).

In 2022, the garden was expanded by 1.15 ha after the addition of a neighbouring erf, purchased in 2018 by the World Wide Fund for Nature South Africa (WWF-SA).