Maritime archaeologists in Sweden say they have found a sister ship to a famous 17th-century warship that sank and is now on display in a Stockholm museum.

Applet (Apple) is the sister ship of the Vasa, a royal warship that was raised in 1961 after more than 300 years under water in Stockholm harbor.

In 1659, Aplet was sunk to form part of an underwater barrier designed to protect the Swedish capital from enemy fleets.

The exact location of the wreck has been lost over time, but maritime archaeologists working at Vrak, Stockholm’s Shipwreck Museum, confirmed on Monday that the wreckage, first discovered last December, is in fact an applet.

Experts who discovered the wreckage near Vaxholm Island, east of the capital, were able to confirm it was an applet based on wood samples and archival data, the museum said.

“Our pulses raced when we saw how similar the debris was to Vasa,” said Jim Hanson, one of the archaeologists.

“Both the design and the mighty dimensions seemed very familiar.”

Visitors can see Vasa’s intricate wood carvings at the Vasa Museum, one of Stockholm’s top tourist destinations.

Salvaged part of warship Applet in Vaxholm, Sweden. Photo: Museum of Sunken Ships / Anders P Nasberg / Vrak / Reuters

Experts were able to confirm that the fragment was a long-lost applet by analyzing its technical details, wood samples and archival data, the museum said in a statement.

Several samples taken and analyzed after a second deep dive this spring showed that the oak for the ship’s timber was cut in 1627 – in the same location as the Vasa timber a few years earlier.

Warship Fire Port Applet.  Photo: Wreck Museum / Jim Hanson / Wreck / Reuters
Warship Fire Port Applet. Photo: Wreck Museum / Jim Hanson / Wreck / Reuters

Parts of Applet’s sides collapsed to the seabed, but the hull survived to the lower gun deck. The toppled sides had gun ports at two different levels, which was seen as evidence of a warship with two gun decks.

No decision has yet been made on whether to raise the ship, which would be an expensive and complicated undertaking.

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Applet was built around the same time as Vasa, by order of the Swedish king Gustav II Adolf.

While Vasa capsized and sank minutes after leaving port in 1628, Applet was launched the following year and remained in active service for three decades.

Experts say the Vasa sank because it did not have enough ballast to balance the heavy guns.