The Mira Flores lies on the aptly named Horseshoe Reef, one of the most dangerous stretches of the Rottnest shoreline. She was a German-owned, British-built iron barque of 500 tons and 49 m, launched in 1867. At about 5.30 am on 30 November 1886 the lighthouse lookout sighted her tacking too close to the island; despite desperate attempts she ran onto the shallow reef and became a total wreck. The crew were saved and some cargo was recovered - books, spirits, machinery, furniture, hardware, farm equipment and more than 80 cases of cartridges. The lack of a telephone between the lighthouse and the pilot station was blamed, and the loss contributed to improved communications. Her anchors are now displayed at the Rottnest visitor centre and museum overlook.

Underwater, the stern section survives most intact, sitting in a deep sand hole, while the rest of the hull is broken and scattered across about 60 m of reef heavily grown with kelp. Depths are 4-10 m, and a WA Museum plaque marks the site.

This is a wreck for calm days and patient divers who like following a scattered site through kelp. The surrounding reef supports the usual north-west-coast fish, and visibility can be excellent when the swell is down. Protected historic shipwreck. Anchor carefully: the reef around the site is shallow and breaks with little warning, and the best approach is from the seaward sand. Visibility after a run of calm easterly days can be superb, which is when this wreck is at its best and when the kelp-covered plates are easiest to follow.

Charter boats from Fremantle (Perth Scuba, Bucket List Diver) reach the north coast of Rottnest in about 45-70 minutes depending on the site; private boats launch at Fremantle, Woodman Point or Hillarys. Run west along the north shore past City of York Bay to Rocky Bay and Narrow Neck (about 9 km from Thomson Bay). The site is marked with an underwater plaque; locate by GPS and anchor in sand clear of the reef, which is shallow and breaks in swell.

Only diveable in very low swell - divingwawrecks gives under 1 m - because Horseshoe Reef is shallow and exposed to westerly and north-westerly swell. Marinelife.org.au says it is best attempted in summer and exposed in winter. Choose a calm day with easterly winds.

General pattern at Rottnest: summer brings calm morning easterlies followed by a strong south-westerly sea breeze from late morning, so dive early; winter brings north-westerly fronts and large swell, with clear, calm spells between them. Check the Bureau of Meteorology coastal forecast for swell height and period before committing.

Descend into the sand hole holding the stern section, explore it first, then follow scattered hull sections across the reef (about 60 m of wreckage) through the kelp before returning to the anchor. Agree a turn pressure before descending (half gas, or a third where current is likely), carry a DSMB, and make a 3-minute safety stop at 5 m.

No regular charter - dived occasionally by clubs and private boats on flat summer days. Nearest dive services: Perth Scuba, Bucket List Diver and Dolphin Scuba (Perth/Fremantle) run Rottnest boat trips; there are no dive shops or air fills on the island.