Joanna was a tiny locally built coaster – a two-masted wooden schooner of 34 tons, only 13.9 m (45.6 ft) long, built in 1856 at Mount Eliza on the eastern shore of Port Phillip, one of the small craft that carried lime, firewood and farm produce around the bay in the decade after the gold rush. On 9 July 1857, barely a year old and loaded with bagged lime from the kilns of the southern peninsula bound for Melbourne's building boom, she was lost off St Leonards. That cargo is why she survives.

The bags of lime set into concrete when they got wet, and their weight has pinned the hull to the seabed and protected it from 170 years of storms; the Scuba Doctor notes that the vessel remains well preserved, with the bagged lime, now solid rock, still visible along with ship fittings and crew possessions. On the south side of the site the remains of the rigging, the anchor chain and rope can be seen, and stingrays have taken up residence on the mound. Heritage Victoria has installed an information plinth on the site.

Because the site is small, intact and fragile, it lies within a 100 m radius protected zone: a Heritage Victoria permit is required to dive and anchoring is prohibited, with severe penalties for entering the zone without authority. It is also exposed – 1.5 km offshore, open to northerly and southerly weather, and, unusually for a bay wreck this far from The Heads, subject to enough tidal stream that it should only be dived at slack water. The Joanna is a dive for permitted archaeological visits and, occasionally, supervised heritage tours, not for casual recreation.

It is included here with its sister site the Clarence, 1 km to the north-west, so that boaters and divers on the Bellarine know where the zones are and why they matter: together the two schooners are the best surviving evidence of the small colonial coasters that built Melbourne.

Boat only and permit only. Launch at St Leonards ramp (five minutes) or Indented Head; Queenscliff is 15 km south. Drive Melbourne–St Leonards via the Geelong Ring Road and Bellarine Highway (about 1 h 40 min).

The wreck is 1.5 km offshore and lies inside a 100 m radius protected zone in which anchoring is prohibited and diving requires a Heritage Victoria permit; permitted dives are run from a live boat at slack water with a supervisor's marker. An information plinth has been installed on the site by Heritage Victoria for permitted visitors.

The Scuba Doctor describes the Joanna as very exposed to weather from the north and the south – it sits 1.5 km off a low shore with fetch across the bay in both directions – and says it should only be dived at slack water, because the tidal stream along this part of the Bellarine coast is stronger than at the Clarence closer inshore. Westerlies are offshore and give the flattest water; northerlies and southerlies chop it up and lift the sand. Visibility is 3–8 m, best in the cooler months after dry weather.

Summer boat traffic between St Leonards and Indented Head is heavy.

Permitted dives only: drop at slack water beside the mound in 6 m, read the information plinth, circle the concreted bagged-lime cargo that pins the hull, look along the south side for the rigging remains, anchor chain and rope, and watch for the resident stingrays. No contact with the site. 40 minutes.

Permit only – archaeological teams (Heritage Victoria, Maritime Archaeology Association of Victoria) and rare supervised public heritage dives; no charter.