Tasmania

Tasmania sits south of the Australian mainland across Bass Strait, and its tidal coast wraps the island from the Tamar mouth at Launceston in the north, around Cape Grim and the wild west coast, past Macquarie Harbour and on to Hobart in the south-east on the Derwent estuary. The tide signature is mixed semidiurnal across most of the island, with two highs and two lows of unequal size each day, the bigger swing falling on the lower-low water. Mean range at Hobart on the lower Derwent is about 1.0 metre, climbing past 1.4 on spring tides; the north coast at Devonport and Burnie runs slightly larger swings, around 2.5 metres on springs, because Bass Strait amplifies the open Tasman Sea signal. The wild west coast at Strahan and Macquarie Harbour runs an open-ocean pattern modulated by the long fjord-like Hells Gates entrance. The Derwent at Hobart is a working harbour and the tide changes the day for sailors leaving Constitution Dock for the Sydney-Hobart, fishers off the Tasman Peninsula sea cliffs, and walkers on the long sand beaches at Seven Mile and Clifton. Roaring-Forties storm surge in winter can lift levels 20–30 cm above predicted. The Australian Bureau of Meteorology and Maritime Safety Tasmania publish the authoritative tide tables.