New Zealand is bathed from the west by three major water masses. The boundaries of these masses are called fronts. These can be seen in the diagram as the Tasman Front (TF), Subtropical Front (STF) and Subantarctic Front (SAF). The Tasman and Subtropical fronts are relatively warm surface currents. The eastward flow of warm water splits around the country so that currents flow south-eastwards around the North Island’s east coast, and north-westward around the South Island’s east coast. The Subantarctic Front is cooler. To the south of New Zealand the Subantarctic Front and associated cold Antarctic Circumpolar Current (ACC) hug the deep ocean floor to the east of the Campbell Plateau and Chatham Rise.