Ozone was the fastest and most famous of the Port Phillip bay excursion paddle steamers. Built on the Clyde by Napier, Shanks and Bell in 1886, 79 m (260 ft) long, 572 tons gross and capable of more than 17 knots, she left Britain on 25 August 1886, arrived in Melbourne on 26 November and for nearly forty years carried holidaymakers from Port Melbourne to Queenscliff and Sorrento – the 'Greyhound of Port Phillip'. Superseded by the Hygeia and Weeroona and by the motor car, she was stripped and in October 1925 scuttled in Half Moon Bay at Indented Head to form a breakwater for the small boats of the township.

The steel hulk Dominion, an old sailing ship cut down to a lighter, was sunk about 20 m north of her for the same purpose. What remains is a remarkably accessible piece of Victorian social history. The Ozone's paddle wheel stands clear of the water 150 m off the beach, and beneath it, in 2–4 m, lie the paddle shafts and sponsons, the boilers, the steering quadrant and the bow section, all encrusted and full of small life.

The Dominion's iron hull is lower and more broken but easily found. Because nothing is deeper than 4 m the site is as good a snorkel as a dive, and children can see the paddle wheel from the beach. Marine life is bay-typical and abundant in the shelter of the iron: leatherjackets, wrasse, cuttlefish, seahorses and pipefish in the weed, sea stars and sponges on the plates, and often big schools of juvenile fish inside the hull.

Ozone is the standard first wreck for Geelong and Bellarine trainees and a favourite family snorkel, and it has none of the tidal or shipping complications of the Heads wrecks. It suits absolute beginners, snorkellers and photographers who like shallow, well-lit wreckage; experienced divers will treat it as a pleasant hour rather than a destination.

Drive Melbourne–Indented Head via the Geelong Ring Road, Bellarine Highway and Portarlington Road (about 1 h 45 min; 30 minutes from Geelong). Park on The Esplanade, Indented Head, opposite Half Moon Bay – street parking only, difficult on summer weekends – and walk 50–100 m down to the sand at the southern end of the beach near beach marker 31B. Gear up at the car; it is a short carry across the foreshore reserve.

Enter from the beach and surface swim about 150 m out to the paddle wheel that stands above the water, dropping down alongside it. Boats can anchor on the sand to the north of the wrecks. Toilets and a general store are in the township; the nearest fills are at Geelong or Queenscliff.

The wreck lies on the north-east-facing shore of the Bellarine, so it is exposed to any wind with north or east in it: a strong northerly to easterly puts chop and stirred sand across the site and makes the swim and the shallow wreck unpleasant. An offshore south-westerly gives flat, clear water. Dive at high tide for the extra half-metre over the boilers and paddle shafts – at low water parts of the wreck are awash and the swim is over knee-deep sand.

No swell reaches this far into the bay. Visibility is best in autumn and on cold winter days, 5–8 m; summer weekend boat and PWC traffic is the main constraint, so tow a flag.

Swim out on the surface to the exposed paddle wheel, descend and work around the Ozone from the paddle wheels and sponsons to the boilers and steering quadrant, then follow the hull to the bow section. Cross 20 m north to the Dominion's iron hull and circle it before returning to the Ozone and swimming back to the beach underwater or on the surface with the flag up. 50–60 minutes in 3 m of water.

No boat charter needed. Geelong Dive Centre and Dive Victoria Group use the Ozone for Open Water training and guided shore dives; Bellarine snorkel tours and school groups visit through summer. Most visits are independent shore dives and snorkels.