Penguin Island lies near the southern end of Adventure Bay, just off the base of Fluted Cape, and is one of the most frequently dived sites on Bruny Island. The Marine Life Network guide describes a narrow and fairly steep rocky reef that quickly gives way to sand in 5-15 m, with shallow sea caves, kelp gardens and reef fish. It notes the island is ringed with nets and cray pots, and that the wrasse and leatherjackets are heavily speared, so the site is busy with fishing activity and fish can be shy.

The reef itself is attractive: kelp and brown algae on the upper slope, sponges and small invertebrates on the steeper faces, and the sea caves in the shallows, where shaded walls can carry jewel anemones and encrusting sponges. Weedy seadragons may be found on the kelp edge, and the sand holds stingarees, flathead and sea stars. Little penguins, after which the island is named, nest along this coast and may be seen on the surface.

Swell affects the site and quickly reduces visibility, so it is best on calm days with westerly winds. It is an easy boat dive for Open Water divers and a good introduction to Bruny's east coast before the more exposed Cape Connella or the Friars. Be alert to fishing gear: carry a cutting tool and give pot lines and nets a wide berth, and avoid anchoring on the reef.

Fluted Cape's towering fluted dolerite cliffs rise directly above, making the setting spectacular.

Bruny Island is reached by the vehicle ferry from Kettering (about 35 km, 40 minutes south of Hobart via the Southern Outlet and Channel Highway) to Roberts Point on North Bruny; the crossing takes about 20 minutes and runs frequently, but book or queue early in summer. From Roberts Point drive south across The Neck to Adventure Bay (about 35-40 minutes), where there are boat ramps and a jetty. There are no dive shops or air fills on Bruny – bring filled cylinders from Hobart or Kingston.

Penguin Island is a short boat run (about 5-10 minutes) from the Adventure Bay ramp towards Fluted Cape. Anchor in sand off the reef, clear of nets and cray pots, which the Marine Life Network notes ring the island.

Adventure Bay faces east into the Tasman Sea and is sheltered from westerly and south-westerly winds, so it is often calm when the channel side is choppy. Easterly and north-easterly winds and swell make the bay and the outer sites rough; southerly groundswell wraps around Fluted Cape and Cape Connella. The Marine Life Network notes that swell reduces visibility and strips delicate growth from the shallow reefs.

Best after several days of westerlies; late summer and autumn are the most reliable. Heavy rain has little effect except near creek mouths.

Descend on the reef, follow it around the island at 8-12 m where it meets the sand, then rise into the shallows to look into the sea caves if there is no swell. Watch for nets and pot lines throughout.

No scheduled dive operator on Bruny; Underwater Adventures Tasmania runs South Bruny and Channel boat trips from Hobart; otherwise private boats from Adventure Bay. Pennicott Wilderness Journeys (Bruny Island Cruises) visits the coast by boat for sightseeing, not diving.