Just to the south of Te Mata Peak, on the other side of the little bridge which comes just after the winery is a sharp junction to the left. If you follow this road down for roughly twenty minutes you will find a steep one lane road leading down to a car park next to a picture perfect beach.
In the carpark, there are public toilets for changing and a surf lifesaving center. Apart from this, there isn't too much apart from a vast stretch of beach, wild sand dunes, and the endless ocean. As the beach is so big it doesn't take long to find your personal spot, though I would recommend that if you did want to swim that you swim between the flags. The water does get cold and there are strong currents but in the burning New Zealand sun, it can feel very refreshing. Surfing is also a possibility here.
Also, on the road down to the beach there is a quite well hidden turning to the right which will lead you to Maraetotara Falls; a popular swimming hole for the locals with some rope swings and jumps if you're feeling brave. This turning is very easy to miss so I would recommend using some form of navigation to get there. The walk to the waterfall and pools is an easy ten minutes, but the surface gets very muddy when wet.