After more than 80 years on the seabed, what is probably the wreckage of the British submarine HMS Thistle has been discovered outside Rogaland, Norway.
Published: 16.10.2023Updated: 17.10.2023Author: Beate Hoddevik and Bente Kjøllesdal Rundereim
The discovery was made in connection with a research cruise conducted through the MAREANO-programme, which maps the biology and geology of the seabed. The submarine was discovered this spring, but it is only now, in connection with a new cruise, it has been possible to identify which vessel it likely is.
Another unknown wreck?
When the spring cruise was planned, the researchers noticed some strange structures on the map. Curiosity got the better of the scientists and a station was set up. It had to be clarified whether it was a geological structure or a wreck that nobody knew about.
The MAREANO-project is a cooperation between the Institute of Marine Research (IMR), the Geological Survey of Norway (NGU) and the Norwegian Mapping Authority. The aim is to thoroughly examine the seabed – and when strange structures appear, they must be examined more closely.
Curiosity got the better of the scientists and a research location was set up. Was this a geological structure or a wreck that nobody knew about?
The answer soon became apparent: When exploring the seabed with an underwater camera, a ship wreck appeared on the screen in the control room. And not just any kind of wreck: it was a submarine.
"It is not very often that I am in the video room when new locations are being investigated, but on this particular occasion my curiosity was piqued well before the video rig was submerged in the water", says senior engineer Kjell Bakkeplass.
And maybe it wasn't so strange. During the voyage, the likelihood that this would be a wreck only grew.
Already, the researchers had discovered four wrecks on the cruise – all but one previously unknown.
"The similarity between the wreck structures we had previously examined, and this one, was striking", he says.
Revealed by camera
The wrecks they had found earlier on the cruise on board research vessel G.O. Sars, were clearly visible structures on the detailed map the researchers from IMR and NGU use when they plan where to set up locations.
"After examining the wreck using a camera, we could quickly establish that it was a submarine", says Bakkeplass.
While the others on board continued the work of investigating what species live on the seabed in this area and what it consists of, Bakkeplass began looking for information about the submarine.
"Since there was no sign of any wreck right here, I checked if there were any submarines that were missing in the area and that could match this wreck."
Two missing submarines
After various possibilities had been examined and experts consulted, including both the Norwegian and British navies, it became clear that it was a British submarine.
But exactly which submarine was still uncertain. It could be one of two: HMS Oxley or HMS Thistle. One sunk just before World War II and the other during.
"Based on the photos, it was established that it was a British submarine, and available information could indicate that the wreck of HMS Oxley was closest", says Bakkeplass.
After they got ashore and contacted submarine experts, the maritime museum, and professionals, however, HMS Thistle became the more likely option.
"After several people had studied the photo, we concluded that it was probably HMS Thistle, but the photo showed too few details for it to be conclusively settled".
A second cruise identified the HMS Thistle
The opportunity to identify the wreck arose when the MAREANO-programme set sail for their research cruise in October.
Before the actual mapping can start, the equipment must be tested. It is done before arriving at the dedicated mapping areas. This time the researchers were to carry out investigations in the Skagerrak, and thus the RV G.O. Sars passed the submarine wreck on its way south.
"In advance, we knew what characteristics we should look for; thus we were able to identify the wreck as “Thistle”, but with a small caveat that it is the Royal Navy who is responsible for the final identification", says cruise leader Kyrre Heldal Kartveit.
After the wreck had been examined, the RV G.O. Sars set course for their preplanned research locations.
"We will map parts of Skagerrak where there is partly challenging terrain with steep slopes and deep underwater valleys so that we can draw a representative map of what is on the seabed in these areas – before it's possible to either establish administrative management units or industries here.
About HMS Thistle's last voyage we know that it ended on 10 April 1940. It was then sunk by a German submarine. None of the 53 crew members survived.
"At that time, navigators used bearings and squares and not GPS as they do today. This means that the position for the sinking is inaccurate", says Bakkeplass.
As for HMS Oxley, it was mistakenly sunk by another British submarine. Two of the crew survived, while 53 perished. Here, too, it is partially unknown where the submarine sank. In addition to the uncertainty about the last surface position, it is impossible to say anything about how far the submarine drifted from the time it was sunk until it ended up on the sea bottom.
Now HMS Thistle rests at a depth of 160 meters outside Rogaland in south-western Norway. Since it is a submarine that was sunk during war, the vessel is to be considered a war grave. According to maritime law, The British Royal Navy maintain right of ownership.
The other six wrecks
In addition to the submarine, six other wrecks were observed during the cruise this spring.
Only one of these was previously known.
"The wreck of the cargo ship Azalea was known before we investigated the area with the video rig. This vessel sank in March 1990, approx. 8 nautical miles NNW of Utsira. Three of the rescue crew died here", says Bakkeplass.
All wreck observations have been reported to Stavanger Museum, which is responsible for wrecks found in this area.
...and an aircraft engine
In addition to the ship wrecks, the voyage also encountered a couple of lost shipping containers along with another curiosity.
"What we thought were parts of an old winch, turns out to be most likely an aircraft engine, also from the days of the war", says Bakkeplass.
MAREANO maps depth and topography, sediment composition, biodiversity, habitats and biotopes, and pollution in the seabed in Norwegian offshore areas.
The Institute of Marine Research, the Geological Survey of Norway and the Norwegian Mapping Authority comprise the Executive Group which is responsible for carrying out the MAREANO field sampling and other scientific activities.
The Programme Group, led by the Norwegian Environment Agency, has the executive responsibility for the MAREANO activities.