The breakwater and training wall at the eastern mouth of the Mersey River were built by the Marine Board and form a shallow snorkel and dive of 2-4 m. The Marine Life Network guide rates it 5 out of 10: the eastern side is sheltered, the western side affected by sediment and tidal current, and there is a kelp forest at the northern end, with small abalone, magpie perch and wrasse and sea stars on a pebble base. Two wrecks lie here: the iron steam dredge SS Agnew (1887) and the Scottish-built G. Ward Cole (1889). The Leven Scuba Club notes bits of wreck and a kelp forest and warns it is diveable only without easterly winds. Local knowledge from Leven Scuba Club members is the best way to get the most out of it, and first-time visitors should ideally dive it with someone who knows the site and the tide.

The central north coast between Wynyard and Port Sorell is the home water of the Leven Scuba Club at Ulverstone, whose site list is the main modern source for it, supplemented by the older Marine Life Network guide. The towns of Burnie, Ulverstone and Devonport sit right on the coast, so many sites are within minutes of a ramp or car park, but the reefs are generally low and weedy, visibility is often 5-10 m, and the coast is open to Bass Strait's northerly and westerly weather.

Devonport is the Spirit of Tasmania ferry terminal, which makes these sites the first and last dives for many interstate visitors bringing their own gear. There is no hyperbaric chamber in the north - the nearest is the Royal Hobart Hospital, about 3.5 hours' drive - so dive conservatively, especially on the deeper offshore sites.

From Devonport cross the Mersey to East Devonport and drive to the eastern breakwater at the river mouth. Walk along the breakwater and enter on its sheltered eastern side; watch for loose stones. From the Spirit of Tasmania terminal at Devonport, all central north-coast sites are within about an hour's drive along the Bass Highway.

North-coast ramps are often shallow and weedy at low tide, so time launches for mid to high tide and carry a sounder, radio and tide tables.

The north-west coast faces Bass Strait: north-westerly to north-easterly winds and westerly swell make it rough, while southerly winds blow offshore and give flat seas - light airs and sunny days are relatively common from January to April. Easterly gales are common in the warmer months and close the eastern faces of Rocky Cape and Sisters Island. Tidal streams run along the coast (eastward on the flood), and several boat sites are only comfortable around slack water.

Diveable only without easterly winds (Leven Scuba Club); the western side is affected by sediment and tidal current from the river.

Snorkel or dive along the eastern side of the breakwater to the kelp forest at its northern end, looking for pieces of the Agnew and G. Ward Cole wrecks. Turn at a third of gas to allow for the swim back and a possibly harder exit, finish with a 3-minute safety stop at about 5 m if the depth allows, and exit where you entered unless an alternative exit has been checked beforehand.

No confirmed commercial dive operator on the north-west coast as of 2026 (older guides mention dive services in Wynyard and Devonport - verify). Sites are dived mainly by the Leven Scuba Club (Ulverstone), other north-west club members and visiting divers with their own boats; Tasmanian Divers (Launceston) runs occasional northern trips.