By Liz Gwynn for the ABC
The SS Nemesis steamship disappeared off New South Wales in 1904. Photo: Supplied / CSIRO / Mitchell Library, State Library of New South Wales
The SS Nemesis is one of thousands of shipwrecks along the Australian coastline.
The 73-metre iron-hulled vessel was carrying coal when it disappeared in a storm 120 years ago, resulting in the tragic loss of all 32 people onboard.
While fragments of the ship and some bodies washed ashore - the hull was never found, and its location remained a mystery until Subsea professional marine services discovered it by chance while searching for lost shipping containers off Sydney.
One of the technicians onboard saw an anomaly appear on his screen at about 1am. It prompted further investigations using a remote-operated vehicle in challenging conditions.
"Our eyes lit up because we could see the height and that it was quite a significant vessel," Subsea managing director Ed Korber said.
"A few minutes into the footage we could see the anchor which was the jackpot for us, and that's when we knew we were onto something significant."
So you think you've found a shipwreck - what happens next?
The CSIRO's RV Investigator conducted detailed mapping of the sea floor and a systematic visual inspection of the entire SS Nemesis wreck using specialised underwater cameras.
It found that while the bow and stern were significantly damaged, other structures belonging to the vessel were still intact and identifiable, including two of the ship's anchors.
"The camera investigation is really important for determining a positive identification of the wreck," CSIRO group leader Matt Kimber said.
That information, along with previous footage collected by Subsea, was passed onto Heritage NSW maritime archaeology experts who were able to identify the wreck as the SS Nemesis, finally solving the 120-year-old mystery.
Several identifying features included the ship's unique hull, the apparent cargo of coal, the number of ventilators, and engine type.
The SS Nemesis. Photo: Supplied / CSIRO / State Library of Victoria
"You have to figure out which shipwreck you've found by comparing the images of the site against historical records," Emily Jateff, from the Australian National Maritime Museum, said.
"Each little piece of the site that's uncovered and understood gives us more of a picture of what happened in the past."
The wreck of the SS Nemesis is protected as a historic shipwreck under the Underwater Cultural Heritage Act 2018.
What do these underwater remains tell us?
Many maritime archaeologists describe shipwrecks as "underwater museums" or "time capsules" because of the important information they provide.
"It's incredibly important to identify a shipwreck because it helps us to better understand Australia and the world's maritime history," Jateff said.
Maritime Museum of Tasmania curator Camille Reynes said shipwrecks contain "an incredible amount of information".
"They tell us what people were eating, and give us an insight into boat building techniques, trading routes or what cargo was being transported," Reynes said.
"They are a capsule and you can discover all sorts of information if you study shipwrecks or the objects onboard."
Efforts to find objects taken from shipwrecks
Ship crew deploy the underwater camera from the back deck of RV Investigator. Photo: Supplied / CSIRO / Hugh Barker
It is understood that items belonging to the crew onboard SS Nemesis are contained within the wreck and will be protected from disturbance or damage under the Underwater Cultural Heritage Act 2018.
Before these laws came into effect, it was common for curious divers or deep-sea "treasure hunters" to take objects or fragments from shipwrecks.
The Maritime Museum of Tasmania has embarked on a new scientific project which aims to find objects taken from sunken shipwrecks.
"Lots of pieces have been recovered and are dispersed across the state in different museums or in private collections, but it means we don't have a compressive understanding of what's out there," Reynes said.
"We are trying to find these objects and fragments and put them in a database because it would be valuable for researchers."
Some of the items that have been found include everyday objects such as cutlery, toothbrushes, shavers, pottery, and metal plates.
"It was another era and people were interested in history and loved treasure hunting because it was exciting," Reynes said.
"We are not judging anyone, we are just wanting to make a big list and catalogue these items so the data can be preserved."
- This story was first published by the ABC