(CNN) — Archaeologists in Sweden have discovered the wreck of a 17th-century warship, the country's Museum of Wrecks, or Vrak, announced Monday. Äpplet was one of four warships created on the order of King Gustavus Adolphus in 1625, along with the Vasa, which famously capsized on its maiden voyage.
Unlike the Vasa, whose salvaged wreck is now a Stockholm museum, the wreck of the Äpplet had long eluded marine archaeologists.
Äpplet was the sister ship to Vasa, which famously sank on its maiden voyage.
Both ships were created by shipbuilder Hein Jacobsson, with Äpplet an improvement on the poor design that made the Vasa unstable, the museum said in a statement.
After service in Europe's 30 Years' War, Äpplet was deliberately sunk in Vaxholm in the Stockholm archipelago in 1659, when it was deemed unseaworthy.
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Working with the Swedish navy, Vrak's marine archeologists initially discovered the wreck in December 2021, but they only identified it as Äpplet in spring this year, after a more in-depth study of the ship's dimensions, construction, wood samples and archives.
Patrik Höglund, a maritime archaeologist at Vrak, told CNN that the discovery was "amazing" because they thought "nothing was left of wrecks in the area."
The oak used for Äpplet's timber was felled in the same place as the wood for Vasa, further pointing to the wreck's identity.
The seabed in the area had been covered with stones in the 1800s and dredged in the early 1900s, so archaeologists thought there wasn't anything else to find, he explained.
In a statement, Jim Hansson, a maritime archaeologist at Vrak who also worked on the discovery, said the team's "pulses spiked" at the similarities between the wreck's dimensions and construction and those of Vasa.
Analysis of the wreck found that the oak for its timber was felled in 1627 in Stockholm's Mälaren Valley, which is also where Vasa's timber was sourced.
Vrak archaeologists previously thought two shipwrecks found off Vaxholm in 2019 were the remains of Äpplet, but investigations revealed them to be the ships Apollo and Maria, built in 1648.
Most of the hull to the height of the lower battery deck has been preserved, protruding six to seven meters (20-23 feet) from the seabed, according to the museum.
The team made dives to the wreck to take samples.
Talking about the significance of the discovery, Hansson described it as "another key piece of the puzzle in the development of Swedish shipbuilding."
Höglund added in a statement that Äpplet will help them understand how the "large warships evolved from the unstable Vasa to seaworthy behemoths that could control the Baltic Sea -- a decisive factor in Sweden's emergence as a great power in the 1600s."
Äpplet's wreck lies in a protected military area, which means diving is prohibited unless accompanied by Swedish navy divers. There are no plans to salvage the wreck, Höglund told CNN, but they will make a 3D image of it.