The Norma is one of Adelaide's most interesting historic wrecks. She was a steel four-masted barque built in Glasgow in 1893, of about 2,122 tons and 85 m (278 ft) long, and was loading wheat in the Gulf ports for Europe when she met her end. On 21 April 1907, while anchored off Semaphore waiting for a favourable wind with around 31,000 bags of wheat aboard, she was struck amidships by the iron barque Ardencraig, which had misjudged distances in heavy rain.

The Norma sank in about 15 minutes, with the loss of the ship's carpenter. Soon after, the steamer Jessie Darling misread the distress signals and struck the submerged wreck, sinking in eight minutes before being refloated. Because she lay so close to the shipping approaches to Port Adelaide, the wreck was dynamited, and today the Norma is spread over a large area of seabed in about 14 m.

Sources describe twisted metal lying on the bottom, with big recognisable parts still visible, including the bow section. An underwater interpretive plaque marks the site as part of the state's heritage trail. Her figurehead, a druid priestess from Welsh mythology, was later found in mangroves at Gawler Point and is now at the SA Maritime Museum.

The wreck is a fish magnet. The Federation calls the fish life prolific, and divers report large schools of bullseyes and King George whiting, frequent wobbegongs, magpie perch, old wives, boarfish, snapper, yellowtail, morwong and goatfish, plus curious cuttlefish. The Norma is rated for advanced divers because of strong tidal currents, variable visibility and the nearby shipping channel.

On a calm slack tide, though, it is a rewarding and historically rich dive, best suited to experienced divers with good boat support.

Boat access only. Launch at the North Haven boat ramp (Lady Gowrie Drive, North Haven; multi-lane ramp inside the marina, large trailer park, toilets), about 25 minutes north-west of the Adelaide CBD. Exit the marina and run west into the gulf to the GPS mark.

There are no public moorings. The wreck lies close to the Port Adelaide shipping approaches, so keep a lookout for large vessels, anchor clear of the channel and never leave the boat unattended – local shops stress that surface support is essential here.

These northern gulf sites are open to wind from most directions and need a calm day: easterlies are best, while westerlies, south-westerlies and the summer sea breeze (usually from late morning) build a steep chop. Tidal currents are the key issue – both the Dive Shack and the Marine Life Network describe strong tidal currents, so plan the dive for slack water, ideally on a neap 'dodge tide' when the water barely moves. Visibility is variable: it can be good on calm, clear days but is often fair to poor, especially after westerly blows, after rain (Torrens and Port River outflow) and when divers stir the bottom.

Watch for shipping movements in and out of Outer Harbor.

Drop a shot onto the wreck using GPS (the marker buoy is about 25 m west), descend at slack water and explore the spread-out wreckage at 13-14 m, looking for the recognisable bow section and the interpretive plaque. Stay close to the shot line in case current picks up, and ascend on it with the boat following.

Protected under historic shipwreck legislation: do not disturb or remove artefacts.

Flinders University Underwater Club (FUUC) runs club dives from North Haven; Diving Adelaide joins some of these; occasional Adelaide shop and club trips; private boats from North Haven.