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By Matt Marrison, CSIRO and Emily Jateff, Australian National Maritime Museum 2 June 2021 6 min read

In 2017, researchers on board our research vessel (RV) Investigator made an important heritage discovery during a transit voyage from Sydney to Broome. They located the wreck of SS Macumba, a merchant ship sunk by Japanese seaplanes during World War Two (WWII), its location unknown for 74 years.

Our Research Vessel (RV) Investigator uses advanced mapping technology to help put Australia's maritime and cultural heritage on the map. Image: Wild Pacific Media.

SS Macumba is one of five shipwrecks of national significance located and imaged since 2015 using technology on board RV Investigator.

This research is helping uncover past lives and livelihoods, and is delving deep into the history of our continent - from both our recent and distant past.

Putting maritime heritage on the map

There are an estimated 8000 shipwrecks off the coast of Australia, dating from the 1600s to present day. Only about a quarter have been located.

In collaboration with maritime heritage groups, RV Investigator has been helping add to the list of located shipwrecks. We discovered SS Macumba in 2017 and SS Iron Crown in 2019. Both were merchant vessels sunk during WWII.

These are their stories.

SS Macumba

SS Macumba was a steel steamship built in the United Kingdom in 1919. The merchant ship was purchased in 1920 by the Australian United Navigation Steam Company Limited (AUNSC) and operated as an interstate freighter in the AUNSC east coast timber and coal trade.

In August 1943, while transporting a cargo of general supplies from Sydney to Darwin, SS Macumba was attacked by two Japanese seaplanes. Despite return fire from both SS Macumba and escort vessel HMAS Cootamundra, the aircraft succeeding a making a direct hit on SS Macumba, causing the vessel to lose power and begin taking on water. Crew attempted to keep the vessel afloat and bring it under tow. However, within an hour they were forced to abandon ship. SS Macumba went down by the stern.

Three crew were lost in the sinking of the vessel.

SS Macumba was a 92-metre merchant vessel sunk off the Northern Territory coast during WWII. Image: Australian War Memorial 303559.

Bathymetry imaging showing the wreck of SS Macumba, with damage to the ship hull, lying on the seafloor.

In October 2017, during a transit voyage from Sydney to Broome, researchers on board RV Investigator located the wreck of SS Macumba in the Arafura Sea in 40 metres of water. Multibeam echosounder (sonar) and drop camera imagery of the wreck confirmed the identity of the vessel.

As a result, SS Macumba is now protected under the Commonwealth Historic Shipwrecks Act 1976.

SS Iron Crown

SS Iron Crown was an Australian merchant vessel built in in 1922. During WWII, the steel screw steamer was owned by the Scott Fell Shipping Company and was contracted to the mining company Broken Hill Proprietary (BHP) to transport manganese and iron ore from Whyalla, South Australia, to Newcastle, New South Wales.

On 4 June 1942, while exiting Bass Strait en route north, it was torpedoed by Japanese submarine I-27. It sank within minutes and 38 of its 43 crew lost their lives. The vessel is significant as one of only four WWII shipwrecks in Victorian waters. It was also the only ship to be torpedoed by a submarine in Victorian waters.

SS Iron Crown was a 100-metre merchant steamship that was sunk off the Victorian coast during WWII. Image: South Australian Maritime Museum.

Bathymetry imaging showing the wreck of SS Iron Crown, with bow to right, lying on the seafloor.

In April 2019, a team on board RV Investigator began the search for SS Iron Crown. The survey area was based on archival research by the Maritime Archaeological Association of Victoria and Heritage Victoria. Researchers discovered the wreck just before ANZAC Day 2019 and it was found lying in 670 metres of water.

Later that year, on Merchant Navy Day in September, a memorial was held at the Shrine of Remembrance in Melbourne for families and descendants of the crew of SS Iron Crown. The memorial was attended by more than 50 relatives of those who had been on the final voyage of SS Iron Crown.

Other shipwreck discoveries

Teams on board RV Investigator have also discovered the historic wrecks of the barque sailing ship Carlisle, lost in 1890 and discovered in 2016, and SS Federal, lost in 1901 and discovered in 2019.

During a 2019 research voyage to the Coral Sea, researchers on board RV Investigator surveyed the site of the aircraft carrier USS Lexington and identified the likely location of the wreck of supply ship USS Neosho. Both vessels were lost in WWII during the Battle of the Coral Sea.

Voyage participants and crew on RV Investigator hold a memorial service after locating the likely resting place of USS Neosho in the Coral Sea. Image: Huw Morgan.

Technology to map the deepest ocean

RV Investigator has three complementary multibeam echosounders (MBES) systems that are used to map the seafloor. Two systems are permanently fitted to the ship, while a third can be added for high resolution mapping in shallow water. The three systems provide the capability to map to any ocean depth in our region, from shallow coastal areas to the deepest parts of the ocean.

MBES send acoustic signals – sound waves – down from the vessel to bounce them off the seafloor. The time taken for the signal to return to the ship allows the water depth to be calculated. This bathymetry (ocean depth) data is used to generate maps and charts of the seafloor.

Bathymetry data provides topographic (shape and form) information for both the seafloor and features on the seafloor. Such information is vital for maritime heritage surveys, where researchers are looking for objects whose size, shape or location seem out of place on the seafloor.

The advanced capabilities of RV Investigator mean that seafloor mapping and heritage surveys can also be undertaken remotely, with researchers on shore reviewing data in real time and working in collaboration with those at sea.

MBES also collect another type of data called backscatter. Backscatter data a measure of sonar intensity and is used to differentiate between different types of seafloor, such as hard rock or soft sediment. Importantly for shipwreck surveys, backscatter can also be used to identify hard objects that may be lying on soft surfaces, even where those objects may be partly buried by seafloor sediments (such as a shipwreck).

RV Investigator can also deploy a portable drop-camera system to inspect seafloor features. This camera takes both still and video imagery and has been used to help identify several shipwrecks.

Uncovering an unbroken connection to country

The cultural heritage being uncovered by RV Investigator stretches back far beyond European settlement of the continent. The ship's MBES systems can produce high resolution imagery of shallow coastal areas around the continent. This imagery can reveal landscapes that were above water when sea levels were lower in times past.

Seafloor mapping by RV Investigator has uncovered Indigenous landscapes and cultural heritage sites during collaborative projects with Traditional Owners and marine park managers.

In 2019, Parks Australia engaged with local Indigenous ranger groups during planning for a seafloor survey in an Australian marine park. As part of this process, and following the mapping work, Traditional Owners were consulted. This engagement is recognised as an important part of science on sea country, helping lead to collaborative research and knowledge sharing, as well as positive management outcomes.

At the end of the voyage, Traditional Owners visited RV Investigator in Darwin to view imagery and vision from the mapping and camera surveys of their sea country.

The seafloor mapping of the area showed cultural heritage sites and landscapes recorded in the stories of the Traditional Owners. These areas had been submerged by rising sea levels thousands of years ago. This mapping illustrated the unbroken relationship between the Traditional Owners and both land and sea country.

A future of more discoveries from our past

Identifying, protecting and preserving cultural heritage from both our recent and distant past is an important priority for all Australians. RV Investigator delivers a powerful tool for deep-water archaeology and cultural heritage surveys.

With only a fraction of Australia’s vast marine estate mapped to a modern standard, we still have much more to discover.


RV Investigator is part of the Marine National Facility, a national ocean research capability funded by the Australian Government and operated by CSIRO on behalf of the nation.


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