Three Hummock Island, in the Hunter Group off Tasmania's north-west tip, is rated 7 out of 10 by the Marine Life Network guide as a remote adventure with rugged coastal scenery. The island is granite - rare on the north-west coast - and at Chimney Corner large cubed boulders form swim-throughs in 10-15 m. Old wives and small crayfish are recorded, with a variety of fish and invertebrates in the crevices and deep drop-offs along parts of the shoreline. The guide describes it as extremely remote and still being explored, and it also mentions nearby Trefoil Island, dived only on its eastern side in easterly weather, as another Hunter Group prospect. Above water the island is a place of rugged granite headlands, and landing requires the leaseholder's permission. Expect to be entirely self-sufficient for a trip here, with a sounder, radio, EPIRB and spare fuel, and a plan for sheltering if the weather turns.

Circular Head, the far north-west corner of Tasmania around Stanley and Smithton, faces the full sweep of Bass Strait and the tidal flows that pour between the mainland and the Hunter Group islands. Few divers visit: there is no dive shop or air station west of Burnie that can be confirmed, so divers bring everything with them, and the Royal Hobart Hospital chamber is around five hours away by road. The reward is clean, rarely dived water and marine life that includes species more typical of Victoria and South Australia, such as warty prowfish and weedy seadragons in the sheltered bays.

Three Hummock Island lies in the Hunter Group off the far north-west tip of Tasmania. The Marine Life Network guide says access requires a private yacht or large shark cat, launched from Duck River at Smithton or Old Port Road at Montagu; the shallow channel to the open sea needs extreme care at low tide. Allow 1.5-2 hours each way.

The island is privately leased, so do not land without permission, and plan fuel for the return trip against the tide.

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.

Very exposed to westerly swell and strong tidal streams through the Hunter Group; only in exceptional calm.

Anchor in the lee, explore the cubed granite boulders and swim-throughs at 10-15 m, and look for deep drop-offs along the shoreline. Turn the dive at half gas (thirds where current or overhead sections are involved), deploy an SMB before surfacing for the live-boat pick-up, and complete a 3-minute safety stop at about 5 m where depth allows.

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.