The Neptuna was the ship whose destruction became the defining image of the bombing of Darwin. Built in 1924 by Krupp's Germaniawerft in Kiel as the Rio Panuco, later the Neptun, she was a 5,952-ton motor cargo ship operated by Burns Philp as the Neptuna. On 19 February 1942 she was alongside Stokes Hill Wharf unloading a cargo that included around 200 depth charges, TNT and other munitions.

In the first raid bombs exploded in her saloon and engine room; as her crew tried to abandon ship the depth charges detonated, throwing debris across the harbour and sending a column of smoke and flame hundreds of metres into the sky. Forty-five people died - 36 crew and nine wharf labourers - and the explosion wrecked the wharf itself. The 19 February 1942 raids - two waves of Japanese carrier and land-based aircraft, the first and heaviest attack ever made on mainland Australia - sank eight ships in the harbour and killed more than 230 people.

In 1959-60 the Japanese firm Fujita Salvage cut most of the wrecks down to or below the waterline for scrap, so what divers find today is usually the lower hull, machinery that was too heavy to lift, and the cargo that the salvors were not permitted to remove. The Neptuna was among the ships Fujita removed, and marinelife.org.au describes her as almost completely taken away by the salvors. What remains are scattered pieces of the steamer near the old wharf, lying close to the Stokes Hill Wharf artificial reef under the fishing platform.

It is not a structured wreck dive but a site of real historical weight, and it is usually done as part of a dive on the wharf reef rather than for itself. Visibility beside the wharf is often poor and fishing activity is heavy, so it suits experienced local divers on a good neap.

Boat. The remnants lie beside Stokes Hill Wharf at the Darwin Waterfront; operators reach it in minutes from Cullen Bay or the Waterfront, and the Stokes Hill / Frances Bay public ramp is a few hundred metres away. The wharf is an active tourist and fishing platform, so boats must stay clear of lines and berthed vessels; do not attempt to dive from the wharf itself without approval from the Darwin Port authority.

Parking at the Waterfront, with cafes and toilets on the wharf.

Tide is everything in Darwin Harbour: the spring range is 7-8 m and tidal streams run hard through the harbour, so diving is generally only possible on neap tides (range under about 3-4 m), timed to the slack at high water when clearer ocean water sits over the site. Spring tides bring strong currents and silt-laden water with near-zero visibility. The dry season (May-October) gives the most consistent conditions; the south-east trade winds can chop up exposed water in the afternoon, so mornings are best.

In the wet season (November-April) run-off from the rivers and creeks drops visibility, afternoon storms build quickly, and the harbour is in cyclone season; box jellyfish are present October-May.

Descend at neap high-water slack beside the wharf, explore the scattered plates and fragments on the bottom and link the dive with the Stokes Hill Wharf artificial reef under the fishing platform. Stay low and together in the poor visibility and surface well clear of the wharf and its fishing lines.

Darwin Dive Centre and Dive Darwin run harbour wreck charters only on neap-tide windows (typically a few days either side of each neap, weekends favoured); Darwin Sub Aqua Club dives it on club neap-tide days (members plan dives at Thursday meetings at the Darwin Ski Club). No daily schedule.