This is the Manukau Heads Signal Station that provides radio contact with vessels using the entrance to the Manukau Harbour. Viewed here from a platform 244m above sea level. It is the perfect place to appreciate the shifting sand bar just outside the harbour entrance. The Manukau Heads narrow opening to the Tasman Sea provide the only route in and out of the harbour for the mass of water shifted by the tides. The harbour is about 390 sq km, and the water level in the harbour varies by up to 4.4m. It is a very treacherous piece of water to sail through.