In 1956, the wreck of the Swedish warship VASA was located by the engineer and amateur archaeologist Anders Franzén after many years of searching for historic wrecks of the Swedish navy by systematically core-sampling the sea bed. The discovery became widely known and a celebrated event in the public sphere, but it still took few years to gather enough support from influential people to realise the lifting. On 24 April 1961 in front of thousands of people this feat was finally accomplished.

Up to this day, research is still ongoing. While the first studies were very much focused on the hull itself and the vessel's historical context, most of the 40,000 objects recovered from the ship have not been studied yet. In recent years, the armament became one of the research questions, i.e. an experimental archaeology project involving the reconstruction and testing of a gun to find out more about the capabilities of early 17th century Swedish gunnery. Another research question were the many provenances, from which the timber was sourced, sheding light on forest management and timber imports.

The VASA is best known for her disastrous maiden voyage on the 10th of August 1628. For a very short time, she was the most powerful warship in the Baltic Sea - possibly the world - and the pride of King Gustav II Adolf's navy, who heavily invested in his fleet. At that time, Sweden was at war with the Kingdom of Denmark, the Polish–Lithuanian Commonwealth, and the Russian Empire. The construction of a large warship like VASA - a ship of hitherto unknown proportions - was connected with the hope to turn the war effort in Sweden's favour.

However, due to a construction error, the vessel was extremely top-heavy and heeled over even at small gusts of wind. When hit with a somewhat stronger gust, the vessel heeled so far over that water poured into the open gunports on the lower gundeck. VASA began to capsize and sink. Of 300 crew members, soldiers and guests only 30 survived.

Blame
In the wake of this event, an inquest was made. Captain Söfring Hansson was imprisoned and interrogated, as were several officers, and the Dutch shipwrights Arendt de Groote and Hein Jacobsson, who took over the shipyard after the death of Master Henrik Hybertsson, who succesfully built many ships for the Swedish navy. During the interrogation it emerged that neither the ballast nor cannon shifted and that the sinking occured as a consequence of a faulty design, blamed on the deceased shipwright.

As we know now, a deviation from Hybertsson's original plan with the creation of an additional deck to accommodate 24-pounder guns made VASA extremely top-heavy, This modification was expressly requested and approved by the king himself.

After VASA was raised, the wreck was placed into a concrete pontoon and supported by shoring struts. The wreck's interior was still filled with silt and over 40,000 objects, which were excvated in 1961. The hull was sprayed with water continously during this process to prevent the waterlogged timber from drying out. After the excavation of the interior, VASA was now ready to be treated with polyethyleneglycol (PEG), a synthetic wax-like substance, which is soluble in water and diffuses into the hollowed-out wood structure of waterlogged timber to stabilise it from within. At the wreck was too large to be placed into a water tank with the conservation fluid, the PEG had to be sprayed onto the wreck, which is considerably more time-consuming. The PEG-spraying started in 1962 and lasted for 17 years, followed by another 9 years of slow air-drying. Although the conservation effort was largely finished in the late 1980's, it has to be kept in mind that the degradation is only delayed, but never entirely halted.

This became apparent when degredation occurred as a result of sulphur and iron compounds, which have formed in the wood structure and weakened the hull stability. Several measures were taken to mitigate the impact, e.g. by the replacement of iron with steel bolts, by controlling the humidity and temperature, and by increasing the interdisciplinary knowledge base. Research on how to optimise the conservation effort is still ongoing.

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