In September 2004, ProMare carried out a survey in Norway in cooperation with the Norwegian University of Science & Technology (NTNU) and the Norwegian Geological Survey (NGS). The objective was to locate World War II aircraft wrecks in Trondheim Harbor based upon anomalies detected by a high-resolution bathymetry survey by the NGS.

Previous research indicated that this area would yield an abundance of material, particularly from the Second World War. Acoustic data collected by the NGS indicated that there were dozens of anomalies that might signal the location of aircraft wrecks. The team, consisting of specialists from ProMare, NTNU, and NGS, reviewed the data to determine the most promising targets to be investigated using a remotely operated vehicle (ROV).

The primary survey tool was a Sperre ROV provided by NTNU. 16 targets were investigated during the survey. Six of the anomalies were determined to be geological features. Five of the targets were modern debris, while two of the anomalies were known airplane wrecks from World War II–one Bristol, and one Sunderland. The most significant discovery was two previously unknown shipwrecks in Trondheim Harbor.

The first shipwreck discovered was a wooden boat with a metal railing around its upper deck/gunwale. Tires, used as fenders, were scattered around the wreck. The second wreck was a double-ended, wooden boat with no engine. The site is at 38 meters depth. The overall length of the vessel is about 15 meters, and the frames inside the hull are clearly visible from above.

The third major discovery of this short survey was the identification of a previously unknown coral reef within the harbor area. ProMare plans to return to document additional World War II aircraft near Trondheim.

Lake Tinn – Hitler’s Sunken Secret

HYDRO (2005)

One of the most daring clandestine operations of World War II was the 1944 sinking of the Norwegian ferry Hydro, with its purported cargo of heavy water destined for the Nazis’ secret atomic bomb project. Heavy water is a form of water with a unique atomic structure and properties coveted for the production of nuclear power and weapons. Although the mission was declared a success, no one has established whether heavy water was actually on board. In cooperation with NOVA, ProMare plunged 1,300 feet beneath a remote Norwegian lake to find the answer to “Hitler’s Sunken Secret. ”

Exploring the bottom of Lake Tinn with a remotely operated vehicle, ProMare, NOVA and Sperre AS located the well- preserved ship along with evidence of a mysterious cargo in steel drums. Analysis of the contents of one of those drums solved the longstanding mystery about the role that the Allies played in preventing a Nazi nuclear bomb. The cargo was indeed heavy water. However, the Allies had no way of knowing that the Nazi nuclear program was a civilian program with little funding, and that the military regime had not considered nuclear weapons practical to construct in a time-frame that would allow them to win the war.

Norsk Hydro began producing heavy water at Vemork in 1934. During the German occupation of Norway, the Norwegian resistance made several attempts to stop the Germans producing increased amounts of heavy water. There was an attack in the autumn of 1942 using a glider, which failed. In February 1943, a group of members from the local resistance succeeded, and after meticulous planning, they climbed down the steep valley sides and sabotaged the heavy water facility. The story is told in the Norwegian film “Kampen om tungtvannet” and the American film production “Heroes of Telemark.”

The Germans rebuilt the plant, and in November American bombers flew over Vemork and bombed the valley, but the plant was only partially damaged. This last attack caused the Germans to move heavy water production to Germany. The resistance successfully sabotaged German plans by placing a time-bomb on board the ferry, Hydro, that was to transport the heavy water over Lake Tinn. On February 20, 1944, as she was crossing the deepest part of the lake, the ferry Hydro exploded, destroying the last of the German’s heavy water.

Click here to see the PBS Documentary about this project: “Hitler’s Sunken Secret”

The Lake Tinn Project in the news

The National WWII Museum published an article here.

America’s official Norway site published an article here.



The Telemark Waterway is 105km long and rises to a height of 72m through 18 locks, and eventually passes the cities of Skien and Porsgrunn in south-central Norway before flowing out into the North Sea. The waterway has been used for transportation of people and goods for hundreds, if not thousands of years.

Between 2006 and 2009, while working in the historic lakes, rivers, canals and fjords of the Telemark Waterway, Fredrik Soreide from ProMare and Pål Nymoen from the Norwegian Maritime Museum located more than a dozen historic shipwrecks in a remarkable state of preservation which range in age from the Medieval/Viking Age to the mid-nineteenth century.

In August 2010, an international team from ProMare (US), the Norwegian Maritime Museum (Norway), the Norwegian University of Science & Technology (Norway), and Hafmynd EHF (Iceland) located nearly two dozen, well-preserved shipwrecks in the lakes of the Telemark Waterway in south-central Norway.

To locate the shipwrecks the team deployed a state-of-the-art, autonomous-underwater-vehicle, GAVIA, provided by Hafmynd EHF (, equipped with the latest sonar imaging and inertial navigation systems, coupled with a modular build and a depth rating in excess of 500m. The Gavia vehicle was used in several locations from a vessel during the course of three days onsite, and gathered astonishing images of ships lost for centuries. The Gavia AUV proved to be an invaluable asset during the operations in Telemark due to the very steep walls of the virtually uncharted deep lakes, which would have made surveying with a standard towed side-scan system extremely challenging.

ProMare and the Norwegian Maritime Museum, joined by ROV developers Sperre AS, returned to the Telemark in August 2012 to identify the sonar targets discovered in 2010. The team deployed a custom built ROV from a specially designed deployment barge, both of which were built by Sperre AS. Two days of exploration helped us to shed light on the identities of some of the vessels discovered in previous years. Though it was difficult to specifically date some of the targets without removing samples, we determined that there were a range of types and sizes, including some very interesting cargo vessels. Some of the most famous exports of the Telemark region are timber and whetstones. As the waterway changed over the years to facilitate the increased transportation of these goods – with locks filling in for waterfalls and canals replacing portages – so too did the vessels. We discovered two nearly identical 19th century barges, one of which was still loaded with timber, indicating a standardization of goods transport in this century. In addition, Pål Nymoen dived on an old whetstone wreck for samples. Analyzing this data will give us a better idea of the history and changes to the waterway and trade with Telemark.


TheTelemark Project in the news

Hydro International published an article here.

The Norwegian Maritime Museum published a Press Release here.


Promare Norway

Norwegian seafaring and way of life have been shaped by the country’s rugged and dynamic landscape. Tall mountain ranges that plunge into interior lakes and rivers, a complex coastline riddled by fjords and small islands, and harsh winters have created a culture that has overcome these boundaries to overland transportation through a strong maritime heritage and identity, which ProMare has been dedicated to studying since 2004.

Norway’s dramatic topography, particularly in the mountains of the interior of the country, have made the formation of townships particularly difficult in the past. All but one medieval town (Hamar) was located on the coast. Because of the difficulty of travelling by land, being linked by the waterways was vital to commerce with the interior, which was rich with natural resources.

This is particularly true for Telemark, a county in south-western Norway where we have conducted several seasons of survey and research. The Telemark waterway, initially composed of lakes and rivers joined by portages and eventually connected via canals, allowed for the transport of trade goods from the interior of Norway with the rest of the country and Europe. The whetstones that were one of the region’s most profitable trade items during the Viking Age and middle ages were quarried at Eidsborg (now Dalen) and Lardal. Stone quarried in Eidsborg and Lardal, along with other trade goods such a hide, horn, and timber from the surrounding forests, was loaded onto boats to travel down Lake Bandak and Kviteseid toward the rest of the waterway and the coast. While many of these boats safely passed through this journey, others did not.

Going farther afield, ProMare headed north in 2004 to search for WWI aircraft in the Trondheim Harbor. More information about this, and our other projects, can be found in the links to the right. Despite our discoveries and those of our colleagues at other institutions, there are many aspects of Norway’s rich maritime history that have yet to be discovered. Other interesting avenues for continued study abound, such as the development of vessel-types distinctive of Norway. Because of this, ProMare has been collaborating with Norwegian museums, universities and archaeologists since 2004 to develop a consistent program of research to explore past Norwegian maritime activities and study the archaeological remains of historical and pre-historical vessels in Norwegian waters.


A Short History of Seafaring and Boats in Norway

Norway’s dynamic landscape – characterized by tall mountains, plunging fjords, and many inland rivers – has created a country with a strong maritime heritage and identity.  Spanning thousands of years, the history of boats and seafaring in Norway is both complex and fascinating.   While some techniques have changed little over the past centuries – such as the use of lapstrake construction for wooden boat hulls – others have changed enormously as a result of great advances in technology.  Below are links to more information about Norway’s dynamic maritime past and the boats that tell its story.

Petroglyphs – Evidence of the First Norwegian Boats

Laced Boats

Saami Boat Builders

Viking Ships

Late Medieval Vessels in Norway

Jekts and Inter-Norwegian Trade in the Post-Medieval Period

The Skyss System

The Postal Service

Saami Boat Builders

The Arctic indigenous people of northern Scandinavia are known as the Saami; they live in far northern Norway, Sweden, Finland, and the Kola Peninsula of Russia.  Primarily fishermen, nomads, and reindeer herders in the past, they lived near the northern fjords in heavily forested areas, though they could often migrate as far as 1,000 km a year to the Gulf of Bothnia.  They were gifted shipwrights, focusing their craft on sewn boats that they often sold to their Norwegian neighbors in the past.   Snorri Sturluson (1179 – 1241), an Icelandic historian, wrote of two 24-oared sewn vessels built by the Saami for King Sigurd Slembadiaekn when he was in the north.   Written sources from the 16th century onwards have referenced the Sea Saamis who regularly constructed vessels for their neighbors in Norway(Westerdah, 1985).

Saami who lived in different regions of Scandinavia had different lifestyles and boat building techniques.  The coastal Saami migrated every year across northern Norway and Sweden to the Gulf of Bothnia in the northern Baltic Sea. The few laced boat finds from the northwest are thus from their summer habitation sites and it is theorized that these Saami transitioned earlier to iron fastened boats than their inland counterparts.  The Forest Saami, who lived farther inland and well into what is now northern Sweden, built a very light laced vessel used on the interior lakes and rivers.  An 18th century account records that the vessels were small but suited to the rapids and currents of the local water; they were so light that they could be carried upon the head of one man who used his birch bark bailer as a cushion.  These vessels were used for a comparatively long time and their dissapearance may have coincided with the collapse of the Forest Saami culture  (Westerdah, 1985).

Scandinavians and Russians began to immigrate to Saami territory in the Medieval period, bringing with them their boat building traditions based on riveted clinker technology.  As a result, the two techniques co-existed for centuries (Jasinski, 1991).

Based upon an analysis conducted of the Scandinavian laced boat finds prior to 1985, Christer Westerdahl published a preliminary ethnic classification of laced boat building traditions.  He determined that the Saami built their light craft between the 9th and 19th centuries AD.  They were different from their Scandinavian predecessors in that they were laced with root fibers and reindeer sinews  (Westerdah, 1985).

The Postal Service

Initially called breybarer, the national postal service developed at the same time as the skyss system. Obligation to transport the mail fell once more to private citizens who lived along the route.  As with the skyss system, they were not paid for their labors.  A more formal system was introduced by the Governor of Norway in 1647.  Departures were rare and much of the journey was made overland.  In 1804, an official postal vessel was introduced.  As was used for the skyss system, an åttring painted with the royal monogram and crown, flying a postal flag, was introduced to take mail north from Terråk in northern Norway.  Though weather did not stop the båtpost from sailing, delays by government official preparing missives created a regularly tardy system that played a role in handicapping Norway’s economic development (Bent).

Skyss and the Transport of Government and Church Officials

From early Medieval times and into the Post-Medieval period, government and church business often required officials to travel along the coast on official business.  Due to the fact that neither the government nor the church owned their own transportation, a system known as Skyss was developed in order to transport these officials to and from their business.  Skyss was a system of relay transportation provided by members of local seaside communities with stops generally located at the gjestgiveri.   Much to their angst, the individuals called upon to provide Skyss were not rewarded for their labors.  The system became more structured with the development of the tilseiingskyss network in 1648.  Officials stationed along the route were in charge of obtaining the transport for those requiring it (Bent).

It wasn’t until 1816 that the system was altered.  Though local communities still bore the burden of transporting those on official business for the state or church with no remuneration, other individuals could hire the service at a price based upon distance traveled and the number of men required.  The new skyss-skifte system was managed by the gjestgiveri, now called the skysstajoner, who were no longer required to guarantee the exact hour of the availability of the transport.  By 1860, those providing skyss for members of state and clergy were paid for their labor.  Use of the service gradually declined due to the introduction of steamships and railroads, with the last disappearing in the 1930’s (Bent).

The boat most often used for skiss was the attiring, which looked like a small medieval longship with a fixed mast.  Manned by eight rowers, it could also be used as a fishing vessel (Bent).

Jekts and Inter-Norweigian Trade in the Post-Medieval Period

Between 1450 and 1850, the Nordland Jekt was the primary means of transportation along the Norwegian coast for both people and cargo.  The Jekts, which were generally 100 feet long with a 30 foot beam, could carry 35-100 tons of cargo amidships. The bow was high and blunt and a small deckhouse occupied the stern. One or two square sails were hung from a single mast amidships. Awkward to handle and requiring large crews, some Jekt owner’s replaced the square sails with the more manageable for and aft rig by the 19th century.  In the late Medieval period, the northernmost of the two Bergen harbors would be filled with over 1,000 Jekts and other small craft between May and September (Bent 2012).

Because the expense involved in owning such a large craft was generally too great for any single family, the inhabitants of a village would often be jointly responsible for the cost and upkeep of a single vessel.  The skipper would take personal responsibility for the delivery of the cargo while the mate would manage navigation.  Knowledge of the intricate coastline was handed down orally through seafaring families, and few charts existed.  Sailors relied primarily on natural landmarks, though a book of navigation titled Opskrift paa Coursen og Havene fra Senjen til Bergen was published in the early 19th century that became a standard reference for Jekt pilots.  Though the summer sun allowed for sailors to operate the Jekts around the clock and make long voyages in record time, the short days of winter greatly increased travel time.  No one dared to operate upon the sea in the dark due to the complex and dangerous nature of the coastline.  A journey that could take four days in the summer – such as the 550 mile trip from Saltdal to Bergen – could take four to five weeks in the winter (Bent 2012).

By the end of the 17th century, the Norwegian government, understanding the importance of a well developed national trade network, began encouraging trade by establishing refuge ports and trading centers at a number of villages along the coast.  A law required that the villages have a gjestgiveri, which provided inexpensive meals and accommodation for travelers.  One of the primary appeals of the gjestgiveri was its ability to obtain a liquor license and sell spirits to the weary travelers.  Fortunately, the majority of the villages were located one day’s sail apart and included such towns as Selsøyvik, Støtt, Kvaløy, Bjorn, Grundset, and Sel.  Traders visiting Bergen often stayed in the lofts above the warehouses owned by the merchants they traded with, or in the bondestovene.  Cooking on board the jekts was forbidden by law due to a fear of widespread fire in the harbor (Bent 2012).

Types of Late Medieval Vessels in Norway

Evidence for the ships in Norway that came after the Vikings is scarcer, and more complex, than for Viking vessels. That isn’t to say that there aren’t archaeological examples.  There are, and comparative studies have been conducted of many of them to determine the characteristics of late medieval vessels in northern Europe.  Three major types of cargo ships would have sailed in Norway’s waters between the 12th and 17thcenturies: Nordic ships, cogs, and hulcs (Crumlin-Pedersen 2000, 230-233).  The ships shared construction features, however, particularly the Nordic ships and cogs during the 12th-13th centuries, and the cogs and hulcs during the 14th-15th centuries.  In some cases they could look so similar that during the 1400’s the same vessel could be called a hulc in one place and a cog in another.

Historical sources can provide context for the archaeological remains and reveal previously unknown information.  This is the case with cogs.  However, N. A. M. Rodger raises an excellent point when he states that while abundant, contemporary historical sources “were mostly the work of chroniclers and administrators who were not familiar with the nautical world, had no incentive to be especially accurate, and were writing in a language (Latin) with a more limited vocabulary than English or French, the dominant written languages among seafarers around the British Isles.  For these reasons, it is often difficult to extract reliable information about the design, construction and handling of ships in peace and war” (Rodger 1999, 62).


For more information on cogs and the Hanseatic League, click here.
For more information on nordic style ships, click here.
For more information on hulcs, click here.
For more information about the citations, a short bibliography about Norwegian Seafaring can be downloaded here.