Tasman Island is a flat-topped dolerite island ringed by cliffs off Cape Pillar, crowned by a lighthouse first lit in 1906. Go Dive Tasmania lists it at 10-40 m or more as a remote site beneath towering cliffs for Advanced and Deep divers. The Marine Life Network guide recommends the north-east side near the old lighthouse, in 15-35 m, describing a quick drop-off with deep-water sponges, currents, sea mammals and schooling fish.

The walls drop steeply from a kelp fringe into deeper water where sponges, sea whips and gorgonians take over. Fur seals from the Cape Pillar–Tasman Island colonies are regular companions, and schools of butterfly perch and real bastard trumpeter hang in the current. Whales pass the island during their winter and spring migrations, and pelagic fish are seen occasionally.

The island is exposed on all sides and currents in the passage between it and Cape Pillar can be very strong, so it is a dive for well-prepared groups with an experienced skipper and a live boat. Weather windows are rare, and most divers who dive here do so as part of a planned expedition-style day. The clarity of the water – often well over 20 m – and the sense of isolation make it a memorable dive.

The island's history adds interest: lighthouse keepers and their families lived on the summit for decades, hauling supplies up the cliffs by a flying fox and haulage, remains of which can still be seen from the water. The island is now part of Tasman National Park and landing is restricted. Divers should plan conservatively, carry oxygen and a VHF radio, and have a sheltered fallback site in mind.

Boat access only. Most trips use the Fortescue Bay boat ramp (Arthur Highway to Taranna, then 12 km of gravel on Fortescue Road; national park pass required), which is the closest launch to Cape Hauy, the Hippolytes, Munro Bight and Cape Pillar. Eaglehawk Dive Centre and Go Dive Tasmania run from Pirates Bay at Eaglehawk Neck (or Port Arthur for Go Dive), adding 20-30 minutes each way.

There are no moorings on these exposed sites; boats drift or hover and run a live-boat pick-up. Carry full safety gear, a VHF radio and oxygen – the nearest help is at Port Arthur or Eaglehawk Neck and the chamber is in Hobart, about 1.5-2 hours away.

These are the most exposed dive sites on the Tasman Peninsula, facing the Southern Ocean and Tasman Sea with no shelter from southerly or easterly weather. Divers interviewed by the ABC said the Hippolytes need no swell and a westerly wind, and that such windows may occur only a handful of times a year; Easter weekend was noted as one. Anything more than about 1-1.5 m of south-easterly to southerly swell, or easterly winds, makes them undiveable.

Currents are strong and unpredictable, particularly around the Needle, Tasman Island passage and Cape Pillar; plan around neap tides and expect to drift. Late summer and autumn (February-May) offer the best chances; operators confirm on the day.

Drop on the north-east side near the old landing, descend the quick drop-off to 25-35 m among deep-water sponges, and work along the wall with the current. Ascend gradually and deploy an SMB well before the safety stop.

Deeper sections beyond 40 m require technical training.

Go Dive Tasmania – lists Tasman Island (10-40 m+, Advanced/Deep) as a remote boat site in calm weather; otherwise private boats from Fortescue Bay or Port Arthur.