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It was the largest and fiercest warship in the world, named the Mars after the Roman god of war: But it went up in a ball of flames in a brutal naval battle in 1564, consigning more than 800 Swedish and German sailors and a fortune in gold and silver coins to the bottom of the Baltic Sea
An Introduction to Mars Makalös

Mars Makalös (Magnificent) was King Erik XIV’s greatest warship, unequaled and unrivaled in the world at its time. The mighty ship was a brutal expression of a king with growing ambitions at a time when city-states developed into nations during the late 16th century. King Erik XIV, true to his Machiavellian inclinations, was convinced that a prince must have no other objective, no other thought, nor take up any profession but that of war, its methods, and its discipline, for that is the only art expected of a ruler. This belief gave birth to one of the mightiest and most modern fleets of the world, and drove northern Europe into centuries of war, leading to the Swedish golden era. It also left a legend still alive today: The legend of Mars the Makalös, her might, treasure and the curse. 

The legend of Mars the Makalös was revitalized in 2011 when, after an epic, 20-year wreck hunt, a group of divers finally discovered the wreck site. The discovery of Mars is now considered to be one of the most significant of our time and firmly places Mars as one of the most important historical monuments in Europe.


The Mars Project


The Mars Project is a voluntary scientific maritime archeological project. All participants chose to commit their time without financial compensation for their expenses. Experienced divers, fully cognizant of the myriad of risks involved in such an endevour, executes the underwater exploration.

The Mars Project sets out to explore the Mars wreck site, its surroundings and to investigate the legend. Some of the scientific questions the expedition sets out to further advance our understanding about are: 

  • How was Mars was built and constructed?

  • What were the living conditions of the men who lived and died on board?

  • How was the battle fought?

  • How widespread and intense was the fire onboard at the time of the sinking?

  • Was the hull really painted white?

  • Where are the missing bow section and the legendary gallon figure?

The scientific goals can be summarized to include:

  • Research the historical significance of the Mars wreck site.

  • Share discoveries with local, national, and international scientists, scholars, and museums.

  • Display major discoveries in museums or special exhibitions, while still allowing researchers to work on these discoveries as needed.

The scientific future ambitions include:

  • To further develop deep-water scientific diving methods.

  • To develop tools and methods for non-intrusive archeology including deep-water photogrammetry, 3D scanning, and launch the concept of digital excavation.

  • Together with partners, complete documentaries that capture the compelling history, the furious naval battle, and the modern adventures of explorations as well as the state of the art scientific methods.

  • Together with partners, complete virtual reality applications for scientists and the public.

The Mars Project is conducted over a two to three week period during the summer every year. During this time more than 40 individuals are involved in the project. Eight scientists from different disciplines participate together with professional surveyors, divers, ROV pilots, technicians, boat crew and support crew. On average, 200+ man dives are performed, documenting the site using 4-8k video cameras, still cameras and sonar systems. A tremendous amount of data is generated for the scientists.


The Mars Project website will share some of the findings and give a unique insight into what became one of the world’s largest maritime archeological projects during recent times.


We hope to inspire others to excel in their efforts to explore and discover their surroundings and to never give up on their dreams. The desire to explore is one of the oldest and most important drives of mankind. Without this drive, the world would be static and the future would be repetitious; both dull and predictable.


Why is Mars Unique and Important?


The exploration of Mars is important for a variety of reasons. The opportunity to study a 450-year-old archeological site is uncommon but several factors make Mars unique:

  • Mars was the largest man-of-war of her time. She was a new design with more bronze cannons than any ship before her.​

  • Mars sank during a furious and brutal two-day long naval battle fully, equipped and manned for battle. Mars did not sink due to a design flaw or due to navigational mistakes. She was overwhelmed in battle, and fire broke lose, resulting in a tremendous explosion that took more than 600 men with her down to their watery graves. 

  • Mars is a perfect time capsule, undisturbed and protected by 75 meters of dark, cold water with low salinity and oxygen levels.

  • The state of preservation is unrivaled. The entire wreck including all the wood, cannons, artifacts and human remains rests on the bottom of the sea. 

  • Mars sank in deep waters, 75m or 250 feet, making it impossible to salvage its treasure and cannons during the time of the sinking and many hundreds of years after her demise. She rested undisturbed for 450 years, silently guarding her integrity and her legends.


Mars presents a rather unique opportunity to study an undisturbed 16th-century capital man-of-war. This makes all relevant efforts important; the knowledge accumulated will enhance our current understanding of the ship, shipbuilding, how battles were fought, Swedish society as a whole, as well as culture, life, and death on board.


Finally, the investigation into the very origin of human conflicts and how survivors of these horrific events acclimatized back into normal life as civilians completes a fascinating list of potential research opportunities.

Scientific Partners


The scientific archaeological study of Mars is a part of a multidisciplinary research project at Södertörn University called “Ships at War - Early-Modern Maritime Battlefields in the Baltic.”The study is also a unique collaboration between the Maritime Archaeological Research Institute (MARIS) at Södertörn University, The National Defense College, and the companies Ocean Discovery, Deep Sea Production, and Marin Mätteknik (MMT). An international television documentary has been created to feature the archaeological study. 


The capacity for these diverse organizations to work together on such a project is uncommon and has gained international interest. Companies and universities are responsible for different specialized knowledge. We are convinced that cooperation between academia and industry can give us new insights and perspectives, both of which may generate new scientific results and contribute to strengthening the company’s abilities and competitiveness. However, regardless of all scientific, practical, and economic benefits of our collaboration, what really links those involved in the Mars Project together is that diving, exploration, and solving mysteries is challenging, exciting, engaging and, in a word: fun!

The Wreck Site

Mars lies on the seabed at a depth of 75 m/250 feet. The shallowest point on the hull is 60 m/200 feet deep and the average depth for a diver exploring the site is usually 69 m/230 feet. It takes a dive team about five minutes to descend down to the wreck: Five short minutes to time-travel back 450 years. 


During the descent, one notices very little of the increasing water pressure but the water rapidly gets colder, much colder, and the ambient light disappears gradually, leaving one both chilled and in absolute darkness at depth. The water temperature is stable at depth and rarely warmer than 4°C/40°F even though the surface water during the warm summer months can be as high as 21 °C/70°F.


The visibility at the surface and down to 6 m/ 20 feet is reduced to just a few feet due to algal bloom. unfortunately, the problems of eutrophication, algal blooms, toxic waste, and threatened biodiversity are growing ever greater in the Baltic Sea. Deeper than 21 m/70 feet, the visibility improves and at the wreck, it can be greater than 12 m/40 feet horizontally. Last year, descending dive teams could clearly spot other divers working on the wreck when as shallow as 30 m/100 feet from the surface.


The wreck is encapsulated in cold, oxygen-poor brackish waters with low salinity levels. Currents at the bottom are uncommon and when currents occur, they tend to be mild. The current is not caused by tidal changes but from water movements in general. These mild and infrequent currents limit the corrosion of the site and help to clear away finer silt and sediments. The seabed composition varies around the wreck site. The bottom on the port side is made up of mostly gravel, small stones, and clay, while the area outside the starboard side is more porous and composed of silt sediments, which cover objects and artifacts. A careless diver can easily disturb the sediments and seriously reduce the visibility in this area of the wreck.

Although water and sediment samples were taken close to and from the bottom sediments for confirmation, evidence of galvanic corrosion was easily apparent: Aluminum cylinders containing safety gas are left hanging 3 m/10 feet off the bottom and all of these cylinders corroded noticeably in less than two weeks. The origins of this powerful galvanic reaction is unclear at this time but a common joke among the divers is that the corrosion is caused by the more than 4000 gold coins said to be hidden among the wreckage.

Areas of the seabed are covered with bacterial and microbe growth, suggesting a dead layer of bottom sediments. The white-colored sediment in these areas indicates white sulfur bacteria. The presence of other microbes cannot be ruled out and future samples and studies are recommended.

Deeper into History


Imagine, the year of our lord 1564, the 31st day of May, outside a stormy Swedish coastline.


The smoke from the fires is thick; heat and poisonous fumes from gunpowder are mixed with screams of terror and agony. The sound of blades hitting steel, continuous musket fire and bursting cannonballs is deafening. A cannonball screams by closely and smashes with devastating force into the railing. Wood and metal splinters cut down gun crews toiling at their weapons on the gun deck. The decks are awash in the blood of the injured crew, making footing treacherous as the youngest members of the crew, the 12-year old deck-hands, pour sand on the deck to help the gun crews fight on. On the top deck of Mars, the remaining Swedish soldiers are fighting courageously and repel wave after wave of boarders. The situation is desperate, the ship is on fire, and it’s only a matter of time before the fire will reach the magazines. To surrender, and lower the flag, is unthinkable. This is far from a gentleman’s battle: To be captured equals being put to death in the most gruesome way, as vivid deterrence to others. Only those few of noble blood can hope to be held for ransom. The Danish-Lübeck soldiers are driven by a frightening urgency to capture Mars, claim her and thus get a share of the ship’s bounty. This goal is far more important to the commoner than the royal ambitions of noble lords and Kings. Cannonballs from Mars and her attacker continue to cross the short distance between the ships, locked together rail-to-rail by grappling lines, weaving a deadly spider web of smoking destruction. Forty-pound cannonballs hit with the force of a thousand jackhammers, shattering bridge timbers and turning the interior spaces of the enemy ships into abattoirs. Cries of pain are mixed with howls of aggression and anger from the battling soldiers. Suddenly, a powerful explosion shakes Mars, forcing the deck to lift upwards and throwing the battling combatants to the deck. Marsstruggles in what is clearly the last moment of her life, her eventual demise now a foregone conclusion. This is the end for Mars: the once glorious battleship is sinking. Swedes and Danish-Lübeck alike desperately try to abandon the sinking ship while the heat from the burning Mars causes the water around her to boil like the devil’s own cauldron.  An enormous cloud of steam rises, like a ghost, out of the ocean. Mars the Magnificent is nowhere to be seen.

Swedish War of Liberation

A fragile peace was all that remained after the signing of the treaty 1524 when Sweden broke out of the union with Denmark and Norway. The hatred among the Swedish nobility towards the Danish King Christian the Tyrant did not fade, and the memories of the horrors and humiliation of the Stockholm bloodbath were still fresh in the minds of the people. The mind of the Swedish King Erik XIV was focused on the goal of revenge, the dream of finally breaking free of oppression and the birth of a nation, unchained. The whole situation is reminiscent of the American War of Independence only hundreds of years earlier, and much more brutal.

War and heroism

Mars sank on the 31st of May 1564, after a brutal two-day naval battle involving more than 60 man-of-war ships. Despite this ultimate defeat, Mars succeeded with something extraordinary, something that had previously never happened in history: She sank one of the enemy’s admiralships with her cannons alone. Despite a desperate defense and heroic actions, during the dramatic finale of the battle, Mars finally succumbed and was abandoned by the Swedish fleet. The ship was boarded and fire spread, leading to a tremendous explosion that sent the foremast into the sky like a shooting missile. Mars sank below the surface, still burning, while the water boiled and steam rose around her. Mars was lost but in so doing she gave birth to a legend that survived for 447 years.


Length: 43-45 m/143-150 ft 
Tonnage: Approx. 1800 tones

Mars was likely the largest warship of its time rivaling any nation.

Number of guns: 107

Historical number of guns range from just above 100 to 200 pieces. The Mars Project has contributed to establishing a more accurate number. 

Soldiers: 450
Sailors: 350

Mars is often referred to as the missing link in warship development and design. She was a hybrid between ships designed for boarding tactics and the later gun-carrying platforms. This explains the large number of soldiers on board.

The scientist Niklas Ericsson, the Mars Project, has focused his studies on the size and dimension of Mars. Based on measurements made by the project divers concludes that Mars originally measured somewhere between 43 and 45 meters between stem and sternpost.

Even if we know that the 107, potentially more, guns aboard Mars cannot be compared to a similar number aboard warships in the following centuries, the notion that these were crammed into a ship that only measured around 44 meters between stem and sternpost adds something to our understanding of sixteenth-century naval warfare. Mars was one of the last boarding tactics ships to be built, with high fore- and sterncastles, but at the same time, it was equipped with a large number of brand new muzzle-loading cannons. The ship is thus almost a prototype of the sailing warships that were built in the century that followed.

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