Sign up for our monthly newsletter so you never miss the latest from InDepth!
By Martin Cridge
Header and historical images courtesy of Dirty Dozen Expeditions
The shout from the starboard lookout shattered the silence on the bridge of the British cruiser HMS Suffolk. All the bridge officers immediately rushed to the bridge wing and looked towards the starboard quarter and there they were, the two German ships they had been searching for—the heavy cruiser Prinz Eugen and the battleship Bismarck. The year was 1941.
Scarily for the crew of the Suffolk,the German ships were less than 11 km/7 miles away and their ship was well within range of the 38 cm/15 in guns on the Bismarck and 20 cm/8 in guns on the Prinz Eugen. Realizing the danger, Captain Ellis immediately ordered the wheel on the Suffolk hard over to port and as the rudder started to bite, the British cruiser leant over and began to come around in an arc and away from danger.
The ships were in the Denmark Strait, a narrow sliver of sea between Greenland and Iceland. The Irminger current splits off from the Gulf Stream on the Icelandic side of the strait, clearing the Icelandic side of ice throughout the year. However, the Greenland side, unaffected by the current, features extending and retreating pack ice depending on the time of year. To further reduce the width of the strait, the British had laid a minefield to the northwest of Iceland.
At the time of the German ships’ passage, it was estimated that the navigable area between the ice and the minefield was around 97 km/60 miles. It was in this area that the Suffolk and her sister ship, the Norfolk, were patrolling. Conditions were difficult and in addition to the ice and mines; wind, snow, and atmospheric conditions, all of which could play tricks on lookouts’ eyes, meant false reports weren’t uncommon. The cold air flowing over the warmer water towards Iceland also caused dense fog banks to form off the Icelandic coast. The crew of the Suffolk hoped that one of these fog banks would save them.
The German ships were expected to come from the northeast, and the two British cruisers steamed up and down the Denmark Strait in a northeast/southwest direction. It was the southwest leg that Captain Ellis feared the most, as the German ships would be coming up behind him and would be hard to spot. Although the Suffolk had radar, the radar of that time wasn’t very effective across the stern arcs of the ship.
His worst fears realized, Captain Ellis now hoped the fog the Suffolk was heading into would hide them from the German ships. He had no way of knowing if the German ships had seen him. The first sign that the Suffolk was spotted would be when German shells started falling out of the sky around his ship. The Suffolk was no match for the German ships, her role was to find the German convoy and then direct the heavy British ships that had already left Scapa Flow to intercept. To engage the Germans would be suicide, even if it was just the Prinz Eugen. Although the Suffolk had the same complement of 20 cm/8 in guns as the German cruiser, she was built to the 10,000 ton treaty limit whilst the Prinz Eugen was not—and was, therefore, more heavily armoured.
In the fog, Captain Ellis allowed the German ships to draw past his position before coming around and latching onto their port quarter at a distance of around 19 km/12 miles: the limit of the radar set onboard.
The German ships had been hoping to reach the Atlantic ocean undetected in order to start commerce raiding activities, disrupting the Atlantic convoys to and from the USA and Canada. Now that they had been spotted, Admiral Lutjens on the Bismarck had a choice: he could turn and attack his pursuers, or he could press on and hopefully get into the wider Atlantic where he had a better chance to shake them off. He chose to press on. Unbeknownst to Lutjens, the British battlecruiser HMS Hood and battleship HMS Prince of Wales were steaming out to confront him before he could disappear into the vast Atlantic.
At 05:37 on May 24, 1941, the Prince of Wales sent an enemy sighting report saying they had spotted the German ships at a distance of 27 km/17 miles, and seven minutes later the Hood sent a similar report saying the Germans were now at 23 km/14 miles. Admiral Holland, in charge of the British ships, ordered them to turn 40 degrees in order for him to shorten the range to the German ships. Unfortunately, only the forward turrets of the British ships could fire on the German ships, but Holland knew if he could get closer and turn, he could fire a greater broadside than the Germans could. Also, at greater ranges, he knew that his ship the Hood was in danger of being hit and damaged by a plunging shell due to her lack of deck armour, and that this risk decreased the closer he was to the German ships. He was also concerned about the Prince of Wales—rushed out of the shipyard, she still wasn’t battle ready—in fact, she still had civilian employees onboard trying to fix various issues, especially with her guns.
Holland made another signal, and the two British ships turned another 20 degrees toward the German vessels. Slicing through the ocean swell at 28 knots, both British ships closed in on the Germans, the Prince of Wales 750 m/0.5 miles or so behind the Hood.
The four ships were now just over 19 km/12 miles apart. On the German side, the Prinz Eugen was leading the Bismarck. On the British side, the Hood was leading the Prince of Wales. Holland’s plan was to concentrate the attack on the Bismarck first. At 05:52, the fire gong sounded on the Hood and she fired her first salvo of shells—not at the Bismarck, as planned, but at the Prinz Eugen. The Hood had misidentified the German vessels. The Prince of Wales, realizing Hood’s mistake, immediately started firing upon the Bismarck. Within minutes, all four ships were firing at each other.
The Germans were concentrating their fire on the Hood and quickly found her range. After the third salvo of shells from the German ships, the Hood was hit, possibly by shells from the Prinz Eugen, starting a fire on her boat deck.
Now at around 13 km/8 miles apart, the fifth salvo of shells left the German ships. Whilst they were in the air heading towards his ship, Holland gave another order for the British ships to turn to port so that they could bring a full broadside to bear on the Germans. As the bow of the Hood started to come around, there was a massive explosion, and almost instantly the ship broke in half as a massive column of smoke and fire shot high into the air.
The Prince of Wales, following close astern, had to make an emergency turn to avoid the wreckage of the Hood. As they passed the scene, the stern of the Hood had already disappeared, and the bow rose up and into the sky before slipping back into the deep, dark ocean. In that brief moment, 1,415 people lost their lives. Only three survivors were ever found.
With the Hood gone, the Germans now concentrated their fire on the Prince of Wales. Just after 06:00, a 38 cm/15 in shell from the Bismarck tore through the compass platform, killing or wounding everybody there except the ship’s captain. Having received a number of hits from both the Prinz Eugen and Bismarck, the Prince of Wales made smoke, turned away, and broke off the engagement.
In less than 10 minutes, it was all over. The British had received a bloody nose, which caused a serious loss of morale in the UK when the news broke, but the British weren’t in favor of letting the Germans get away.
Fortunately for the British, the Prince of Wales had managed to hit the Bismarck three times, and two of these hits would prove decisive. One hit forced the Bismarck to shut down two of her boilers due to flooding, which caused her to lose speed. Also, a hit forward caused more flooding that left the Bismarck trailing streams of heavy fuel that the British could follow.
Lutjens knew that he couldn’t carry on his mission without getting his ship repaired first, so just after 08:00, he changed course for France. Suffolk, Norfolk, and the Prince of Wales, still following the German ships, altered course as well. They all headed towards the French coast.
Later that day, Lutjens gave orders for the Prinz Eugen to carry on the raiding mission by herself and gave permission for the ship to detach. Just after 18:00, whilst the ships were passing through a rain squall, the Bismarck turned to confront her pursuers. This unexpected maneuver startled the British, and both the Bismarck and Prince of Wales started firing at each other. Whilst neither side scored any hits, the Prinz Eugen had managed to slip away undetected and head into the Atlantic ocean alone.
Then followed one of the greatest naval chases of all time. Every British naval ship in the area headed out to cut the Bismarck off from reaching the safety of the French coast. In the end, they succeeded, and the Bismarck was finally sunk at 22:40 on May 27.
The Prince of Wales would be repaired and returned to service only to be sunk by Japanese airplanes on December 10, where she became the first battleship to be solely sunk by aircraft in open seas.
The Prinz Eugen ultimately had to abandon her commerce raiding mission due to fuel and machinery problems and headed to Brest for repairs docking on June 1.
The contract for building the Prinz Eugen was placed with the Krupp Germaniawerft shipyard in Kiel, Germany, in November 1935 with her keel being laid down the following April.
In the presence of Adolf Hitler and other select guests, the ship was launched down the slipway on August 22, 1938, to much fanfare.
Also in attendance was the Hungarian Regent, Vice-Admiral Mikios Horthy de Nagybanya, the last Fleet Commander of the Austro-Hungarian Navy, and briefly Captain of the Austro-Hungarian battleship Prinz Eugen during World War I.
The German Navy was originally going to call the Prinz Eugen “Tegetthoff,” after Admiral Wilhelm von Tegetthoff, who had delivered a crushing defeat to the Italian Navy during the Seven Week War in 1866. Hitler, however, not wishing to offend Mussolini and his new Italian allies, decided on naming the ship Prinz Eugen instead.
After her exploits with the Bismarck, the Prinz Eugen spent the rest of 1941 docked in Brest. With her were the German battleships Schamhorst and Gneisenau. There they became the focus of regular bombing attacks by the RAF, and it quickly became clear that their situation would soon become untenable if they stayed in Brest.
Hitler decided that the ships should be redeployed and that they should make for Norway to support operations there. The ships had a number of options for the journey to Norway. Prinz Eugen could retrace her steps and follow the route back through the Denmark Strait that she had taken with the Bismarck, or she could take the shorter but more dangerous route through the English Channel. Hitler decided the ships should make a daring dash through the English Channel.
On February 11, the three German ships and their escorts managed to slip undetected out of Brest and started their perilous journey toward the English Channel. Although both the Schamhorst and Gneisenau hit mines, they all managed to slip by the British forces and, once again, the Prinz Eugen had humiliated the British.
That humiliation, however, was short lived again on February 23. During their journey to Trondheim , the British submarine HMS Trident managed to hit the stern of Prinz Eugen with a torpedo, causing serious damage. After repairs in Germany were completed, the Prinz Eugen spent the rest of the war in Baltic waters. Prinz Eugen saw out the war supporting German forces on the Eastern Front as they were pushed back by the Russians. In March, she fired almost 5,000 shells from her 10 and 20 cm/4.1 and 8 inch guns, bombarding Russian-held positions. Prinz Eugen sailed for Copenhagen on April 19 where she joined the German light cruiser Nürnberg.
As the war in Europe headed towards its conclusion, the Prinz Eugen was ceremonially decommissioned by her crew on May 7, and was taken over by the Royal Navy the following day. From Copenhagen, the Prinz Eugen was escorted to Wilhelmshaven by the British cruisers HMS Dido and HMS Devonshire; once there, the Prinz Eugen was dry docked.
Although the Americans didn’t have a use for the Prinz Eugen, they were keen for the ship not to end up in Russian hands. In the end—to stop the arguments—the remains of the German fleet were divided up into a series of lots which were drawn from a hat. The Americans drew the Prinz Eugen. The Prinz Eugen was commissioned as a war prize into the US Navy on January 5, 1946. She soon departed Bremerhaven for Boston with a mixed American-German crew consisting of 574 German officers and sailors, supervised by 93 American officers and sailors under the overall command of US Navy Captain Arthur H. Graubart.
After an uneventful journey, the Prinz Eugen arrived in Boston around January 22, and the US Navy began examining their new prize. The large, passive sonar array that had proved so valuable to the Prinz Eugen for detecting other ships and submarines was removed and installed on the submarine USS Flying Fish for testing. The ship was then moved to the Philadelphia Navy Yard where investigations of the Prinz Eugen’s fire control system could be carried out, leading to the removal of her front 20 cm/8 in guns.
By May 1, the last of the German crew had left the ship and were returned to Germany. The Prinz Eugen arrived in Bikini Atoll the following month with just a skeleton American crew onboard to be used as part of Operations Crossroads nuclear testing.
For the first nuclear test designated “Able,” the Prinz Eugen was moored around 1,100 m/0.70 miles from the planned zero point above USS Nevada; for the second test, “Baker,” the ship was moored around 1,600 km/ 1 mile from the detonation point under LSM-60. After both tests, the Prinz Eugen was relatively undamaged but—as with other ships that survived the second explosion—she was now highly radioactive. Along with a number of other vessels, the Prinz Eugen was towed to Kwajalein for decontamination and was largely forgotten about until December 21, when she was observed to be listing with her stern low in the water.
Attempts were made to beach the Prinz Eugen on Enubuj Island in Kwajalein Lagoon, which ultimately failed when the ship grounded on a coral ledge just offshore. The ship continued to take on water and capsized in the early hours of the following morning. Due to the radioactive contamination, not much could be done and the ship was left where it was. The ship was resurveyed again in the seventies and found to be radiation-free, although the report noted that all the ordnance still onboard and residual fuel would need to be removed before salvage operations could be carried out; so, once again, nothing was done. The report did state, however, that all the fuel should be removed within the next 30 years whether the ship was salvaged or not.
In the end, it took until 2018 when a US Navy-led salvage team from the Navy’s Supervisor of Salvage and Diving (SUPSALV) successfully removed 229,000 gallons of fuel from 173 tanks on the Prinz Eugen. Using a method called hot tapping, the fuel was pumped onto an oil tanker moored nearby for disposal and recycling. The tanks were then resealed to prevent leakage of any residual fuel left in the tanks.
Diving the Prinz Today
Nowadays, two of the ship’s three propellers can be seen poking out of the water at low tide. The third was salvaged in 1979 and is now on display at the Laboe Naval Memorial in Kiel, Germany. From the stern, the upturned hull stretches out and disappears into the crystal blue water of the lagoon. Divers can drop down to the seabed 12 m/39 ft below neat rows of portholes that allow them to peer into the aft compartments. Toward the bow, the seabed slopes away leaving the bow hanging in mid-water at around 36 m/117 ft.
As divers head toward the bow, two barrels of the aft 20 cm/8 in guns come into view as they lie on the seabed. Above the gun barrels is a hatchway into the wreck that offers divers the chance to explore the aft compartments inside the wreck. As the ship capsized, most of the ship’s upper superstructure was crushed underneath the ship as she rolled over. Some parts of the superstructure broke away, however, and masts and gun directors lie scattered in the sand around the vessel. On the vessel itself, divers can find anti-aircraft guns and torpedo launchers still armed with torpedoes. An open hatch allows divers to view racks of spare torpedoes in their storage compartment.
Various openings allow exploration of the topsy-turvy world inside the vessel. Off the main corridors are cabins with upside down beds and tables fixed to what is now the ceiling with chairs that have fallen to the now floor. Some lines have been laid inside the vessel in the past, but these shouldn’t be relied upon for navigation. Divers glancing out into the blue from inside the ship will often see reef sharks and eagle rays cruising by, and the crevices on the upturned hull are favorite hiding places for the many octopuses that can be found on the wreck.
Venturing deeper into the wreck, machine and generator rooms can be found along with galleys, mess decks, heads (toilets), bathrooms, and storage rooms. Even though the Prinz Eugen isn’t a particularly deep wreck, one’s time underwater soon comes to an end. With so much exploration to do, the time passes quickly.
As we like to say at Dirty Dozen, “So many wrecks, so little time.”
Citizen Science to The Rescue: Getting to the Bottom of Lake Tomarata
Lake Tomarata and the surrounding wetlands near Auckland, New Zealand were mistakenly believed to be low-value habitat with limited–to–no biodiversity. That’s until water quality scientist Ebi Hussain and his posse of citizen scientists took up the case and started collaborating with local partners. Here’s what a team of dedicated volunteers can do.
by Ebrahim (Ebi) Hussain
Header image: Louise Greenshields installing continuous pH and dissolved oxygen sensors. Photo by Ebi Hussain
Lake Tomarata in New Zealand’s Auckland region, is surrounded by an extensive wetland—the only one of its kind in this region. Its ecological significance and rich native biodiversity, including several threatened and endangered species, make the lake and wetland complex unique and deserving of protection. It is dangerously significant that only ten percent of New Zealand’s wetlands still exist.
A very small subset of these wetlands are considered as lacustrine wetlands, making this ecosystem critically endangered; only one percent of this wetland’s original extent remains. The lake itself is equally unique and is the only example of a peat lake system in the Auckland region. The fact that these two very rare ecosystems exist together in one place makes this site extremely special and has set the stage for our most comprehensive project to date.
Both the lake and wetland have been independently studied before, but there has been no ecosystem scale assessment that examines both systems as one interconnected environment. The wetland values are well-described in published literature. However, the ongoing pressures and impacts from the surrounding catchment are not fully understood. The lake has been monitored over time, and the general consensus is that there is limited to no biodiversity values present and the water quality is deteriorating .
Our visits to the wetland and dives in the lake alluded to something more than the degraded systems described. Instead, we uncovered a misunderstood environment with complexities that led to the false assumption that the lake had low ecological value. This highlights the value of citizen science and in particular, divers that are able to regularly document areas that most people don’t frequent.
We wanted to legitimize our findings and debunk the false portrayal of this unique environment. To do this, we wanted to create an open access integrated ecosystem management tool that could be used for collaborative monitoring and restoration. This tool would need to be based on accurate ecosystem scale assessments and integrated into a single geospatial platform where all data could be viewed and interpreted. To create this tool, we needed to map the entire environment as one ecosystem, establish an in-lake biodiversity baseline and current state assessment for both systems, integrate all the data, and develop monitoring techniques that would inform management plans.
This seemed completely unachievable for a group of volunteers, but we did not let the monumental task intimidate us. We drew up a plan, put together a team, and pushed on one step at a time.
Draw Me A Map
The first step in understanding an ecosystem is to map the environment and create a spatial platform to guide in-situ surveys and integrate multidisciplinary data. This project was the first time we mapped aquatic, terrestrial, and transitional environments to create a single ecosystem model.
The challenge with this type of mapping was that we needed to work in three dimensions because the surface and subsurface environments are interlinked. The best way to do this was to use various survey techniques and data inputs for each environment to create an integrated, three-dimensional model of the entire ecosystem.
To map the lake, we used existing hydroacoustic data collected using a variety of methods including sonar, depth sounders, and pressure transducers to create a bathymetric map of the lakebed. We used divers to ground-truth (i.e., check the accuracy of) the bathymetry, and map the shallow transitional areas between the lake edge and the wetland. The result was a high-resolution map of the lakebed and general lakebed characteristics.
We mapped the wetland using drone imagery and existing data inputs. We flew a drone along a pre-programmed geo-referenced grid that spanned the entire sub-catchment to obtain high resolution imagery. This imagery, coupled with LiDAR data, was used to create a three-dimensional point cloud, ortho mosaic, and digital elevation model of the entire sub-catchment.
We combined the surface and subsurface mapping to create a single three-dimensional model of the entire ecosystem. This gave us the ability to visualize both systems as an integrated environment and extract detailed spatial and environmental information. This model would also be used to display and integrate all the survey data. To frame this data into the context of the wider landscape, we overlaid the catchment land use split, overland flow paths, soil types, and ecosystem classification. This allowed for a greater diagnostic power when assessing the potential impacts of changes in the wider catchment.
Assessing Lake Biodiversity
The biggest knowledge gap we faced was in-lake biodiversity. There have been several reports discussing the general health of the lake and discrete ecological surveys, but no conclusive lake-wide assessments. One of the conclusions drawn by a majority of the published literature was that the lake is completely devoid of plants and is overrun by pest fish species.
We used the bathymetry to design a lake-wide survey aimed at assessing habitat quality, macrophytes, key stone species, and benthic flora and fauna. The first survey was to map out specific habitat types throughout the lake; these areas were then plotted on the three-dimensional model. We used the habitat assessments to guide the other biodiversity surveys, since they gave us an idea of where various species may occur.
During the biodiversity surveys, we made some ground-breaking discoveries. Despite the lake being classified as non-vegetated, we have mapped nearly 1 km/0.62 miles of native macrophyte beds along the southern and western ends of the lake. We also found freshwater mussel beds on the eastern side of the lake, which was an amazing discovery, as no one knew these endangered species existed here. Recently, we were lucky enough to find the first juvenile freshwater mussels ever recorded in an Auckland lake.
So far, our findings indicate that this lake is far from a barren waterbody. There are signs of natural regeneration and established populations of endangered species. It is critical that we get this message out and raise the profile of this lake: the more we know about a place, the more we value its protection.
Establishing a Baseline
A baseline state is essential to track changes over time. We wanted to take an integrated ecosystem approach to the baseline assessment rather than focusing on tracking single metrics and using them as a proxy for wider environmental health.
The first step was to use the three-dimensional model we created to define the current extent of both the wetland and lake environments. Tracking changes in extent over time provides information on wetland succession/recession, water level, lake infilling, and habitat change. We used the high-resolution drone imagery to delineate discrete vegetation types across the wetland, and we aim to calculate vegetation biomass in the future. This will allow us to track changes in vegetation assemblages in response to eutrophication, sedimentation, and climate change.
The in-lake biodiversity assessments were used to create a baseline for in-lake health. Ecological response metrics like macrophyte extent, mussel density, substrate/habitat change, and species diversity will be used as a biological sentinel network that integrates the effects of multiple impacts across the ecosystem.
Changes in water quality are pivotal to both the lake and wetland, so it is crucial that we fully understand the current state. To understand the diurnal and seasonal variation in water quality, we installed continuous water quality sensors (temperature, pH, dissolved oxygen, and light) at every meter through the water column; these sensors will log measurements every 15 minutes for a year. This data, coupled with the monthly water quality samples and climate data from the Auckland Council, will be used to create an in-lake process-based model that can be used to understand and predict lake dynamics.
We will also integrate additional data such as bird counts, pest fish surveys, and hydrological studies collected from other agencies into our assessment. This information, along with other geospatial data, can continually be added to the platform as they become available.
Tracking all these parameters creates an early warning system able to detect subtle changes in ecosystem health. This integrated response-based approach is more sensitive than traditional monitoring methods. The in-lake, process-based modelling will continue to be calibrated as we collect more data, which will eventually allow for accurate scenario testing. The end goal is to be able to detect changes early enough that we can test virtual restoration/management scenarios and implement the most effective solution before significant degradation occurs.
Management & monitoring
The key to successful ecosystem scale management is collaboration. We created an open access platform for everyone with a vested interest in this area, not only so they could use the model, but so they could also contribute their own data. We established the baseline ecosystem state—which can be referenced in all future studies—as well as the monitoring tools required to track environmental changes. The last step will be to introduce people to our work and set up collaborative working groups focused on Lake Tomarata.
Currently, we are partnered with the Auckland Council, which has regulatory authority over the area. The Council and Aotearoa Lakes have a joint monitoring and data-sharing agreement which allows both parties to benefit from pooled resources, expertise, and data. We are working with the local communities and tribes from the area to raise the profile of this ecosystem and create an interest that will hopefully lead to proactive lobbying and restoration efforts.
Our integrated ecosystem monitoring design, spatial representation of multidisciplinary data, and ability to scenario-test management options creates a publicly accessible platform for informed collaborative ecosystem monitoring and management.
What makes this effort so special is that it was all done by dedicated volunteers. This project proves that citizen science can stand up to the rigor of commercial standards and in some cases even surpass it. I hope this article will inspire you to take action despite how Herculean the task may appear to be. There is nothing more powerful than a collective of like-minded people applying themselves to a single cause.
Please visit our website Aotearoa Lakes: Citizen Science for Our Lakes for more information on our projects. Note that “Aotearoa” is the Maori (the indigenous people of NZ) name for New Zealand, literally meaning, “land of the long white cloud.”
Check out their 3D model of Lake Tomarata: Aotearoa Lakes Eco-Maps. To get to the Lake Tomarata model, click on the website maps link (above). A banner pops up along the bottom of the screen with pictures of various lakes side by side. Click on the “Tomarata Lake” site which is the 3rd box from the left on the bottom banner.
Facebook page: Aotearoa Lakes: Citizen Science For Our Lakes
Home of Project Baseline
Ebrahim (Ebi) Hussain is a water quality scientist who grew up in South Africa. As far back as he can remember, he has always wanted to scuba dive and explore the underwater world. He began diving when he was 12 years old and he has never looked back. Diving opened up a new world for him and he quickly developed a passion for aquatic ecosystems and how they work. The complexity of all the abiotic and biotic interactions fascinates him and has inspired Ebi to pursue a career in this field.
He studied aquatic ecotoxicology and zoology at university, and it was clear that Ebi wanted to spend his life studying these subsurface ecosystems and the anthropogenic stressors that impact them. After traveling to New Zealand, Ebi decided to move to this amazing country. The natural beauty drew him in, and even though there were signs of environmental degradation, there was still hope. Ebi founded Aotearoa Lakes with the goal of contributing to, preserving, and enhancing this natural beauty as well as encouraging others to get involved in actively monitoring their natural surroundings.
Thank You to Our Sponsors
Why Do Divers Run Out Of Gas?
Not surprising, the answer is more complicated than simply, they neglected to look at their gauges. Here Aussie diving medical...