Conside is the earliest screw-steamer wreck in Victoria and a piece of engineering history. She was a 368-ton iron steamer built at South Shields in 1848, 32 m (105.5 ft) long, powered by an 80-horsepower geared oscillating steam engine – an early and unusual arrangement in which oscillating cylinders drove the screw through gearing – and she is thought likely to have been the first steamship to cross the Pacific, having come to Australia by way of South America. On 14 September 1852, in thick squally weather, she was approaching Port Phillip at her full nine knots when her master mistook the distress signals of a wrecked schooner's survivors on Lonsdale Reef for the lighthouse.

She ran up and over the outer part of the reef and bow first into the inner lagoon, where she broke up. The wreck lies on the extreme south-west point of Lonsdale Reef in about 5 m, on the outer edge of the same reef that holds the George Roper and Holyhead. Very little survives of the hull after 170 years in the break, but divers have confirmed the remains of the early geared oscillating engine on the south-east corner of the site – iron castings and gearing that are archaeologically and technically important as one of the few surviving examples of the type anywhere.

Around them the reef is the usual Lonsdale mix of kelp, coralline algae, sweep, wrasse and crayfish. The Conside is a dive for maritime-history enthusiasts on the flattest days at the end of the ebb, most often tacked onto a Holyhead dive. There is no wreck to swim through, only fragments to find and recognise, and the location on the reef's most exposed corner means it is diveable a few days a year.

It suits experienced Open Water divers already familiar with the Lonsdale Reef sites and comfortable in surge; it is significant far beyond what it looks like.

Boat only. Charters leave from Queenscliff Harbour (Dive Victoria Group, Red Boats, Bay City Charters, Chimney Rock Charters) and Portsea Pier (Dive Victoria Group, Bayplay, Bay City Charters); drive Melbourne–Queenscliff via the Geelong Ring Road and Bellarine Highway (about 1 h 40 min) or Melbourne–Portsea via the Mornington Peninsula Freeway and Point Nepean Road (about 1 h 45 min). Private boats launch at Queenscliff (Larkin Parade) or Sorrento ramps, 10–20 minutes from the site.

Parking is at the harbour or along Point Nepean Road; gear is loaded on the pier or pontoon and the boat times its arrival for the slack-water window, so departures are set by the tide table rather than the clock.

The outer south-west corner of Lonsdale Reef is the most exposed part of the reef, in the break on the western jaw of The Rip. The Scuba Doctor lists it as diveable only on slack water at the end of the ebb (SWE) or on the ebb, never on the flood, and only in swell under about half a metre – the same handful of flat summer and autumn days as the George Roper and Holyhead, but with even less tolerance for surge because the engine remains sit right at the reef edge. Northerly winds are offshore.

Shipping through The Rip is a few hundred metres away and its wash reaches the site.

Combine with the Holyhead: from the outer edge of the Holyhead field work south-west along the reef edge to the extreme point, where the remains of the geared oscillating engine lie on the south-east corner of the site in about 5 m; photograph and return before the flood. 30 minutes, flat day, end of ebb.

No charter schedules the Conside; it is visited occasionally by Queenscliff and Point Lonsdale divers and maritime-archaeology groups on flat days at the end of the ebb, sometimes as an extension of a George Roper/Holyhead dive. Dive Victoria Group and Red Boats can drop divers by arrangement.