Plettenberg Bay, usually shortened to Plett, is the Garden Route at its most seaside: long beaches, dolphins in the surf, white houses on the slopes, and the Robberg peninsula holding the southern edge of the bay. It is more resort-minded than Knysna, but it has enough nature close by to keep it from being just another beach town.
The best reason to stop is Robberg Nature Reserve, where trails run above seal colonies, dunes, cliffs, and Stone Age cave sites. Add a sea safari, a surf session at Lookout Beach, or the forest sanctuaries near The Crags and Plett easily fills a spare day.
It is popular in South African holiday season and can feel polished around the centre. Come outside the peak rush if you can, and use it as an active coastal base rather than a place to sit behind a resort wall.