The harbour is effectively two flooded river systems separated from the Pacific Ocean by Matakana Island.
Approximately 290,000,000 tonnes of water flow through the entrances at each tidal change.
This tidal flow can generate currents of up to 7 knots within the entrance channels.
Shipping movements can take place at any time, day or night, through the main channels.
The harbour is used for many recreational activities, including water skiing, kite surfing, jet skiing, boating, swimming, diving and fishing.