If you really want to feel like a castaway then Harrismith Beach could be your answer. The first thing you'll notice is an old rundown hotel which overlooks a stunning deserted beach, flanked by palm trees all around.
There's a series of steps which lead down to the beach from the cliff top, it's very pretty and usually very quiet here and a perfect place to relax.
There are plenty of lagoons here for a quick dip, just but be wary - there's no lifeguards on duty here. Bottom Bay is also just a short walk away. Harrismith is a stunning location and definitely worth a stop.