The main access at the moment is from Coast Road, south of Wainuiomata. Drive until you reach the sea, where you can park and walk to the beach. If you are really keen you can walk west along the beach and cross the Wainuiomata River if it is safe, carrying on to the prominent rocks on the beach at Baring Head. This is a popular rock climbing spot, good for a picnic, and with a view of the Baring Head lighthouse above.
On February 13 Greater Wellington will be opening a network of walking and mountainbiking trails over the area between the Wainuiomata River, Baring Head, and Fitzroy Bay.
Watch this space for the details.