Over 200 years ago, a sea battle in the Ruotsinsalmi strait near the Finnish city of Kotka resulted in dozens of vessels sinking to the bottom of the Baltic Sea. The cold, fresh water of the strait has kept the ships well preserved, offering a treasure trove of archeological information that few history buffs are even aware of, even within Finland's borders.
Diver Thomas Stenberg will never forget the time he first came across the Ruotsinsalmi shipwrecks.
"It was a great feeling as I was swimming forward to slowly see the stern take shape in the darkness. I had no idea that these old ships were even there. The shipwrecks are so incredibly old," he says.
Battle of Svensksund ended the Russo-Swedish War
The Battle of Svensksund (the Swedish name for the strait) was a naval battle between the Swedish and Russian fleets that took place in 1790. The Swedes dealt out a devasting defeat, which ended the Russo-Swedish War that had started two years earlier. It is still considered the largest naval battle ever to have taken place in the Baltic Sea.
Russian disagreements with the Ottoman Empire had caused it to move some of its Baltic fleet to the Black Sea, so the Swedish king Gustav III saw an opportunity to attack his opponent and make a name for himself.
The Russians lost at least half of their 14,000 men in the fighting, along with ten sail and oar hybrid vessels and schooners, nine half-schooners, 16 galleys, four gun prams and floating batteries, seven bomb vessels, five gun sloops and several other small vessels. The Swedes lost just one warship, five minor vessels and 300 men.
Diver Stenberg says the aftermath is well preserved in the strait to this day – a real diver's paradise.
"There's nothing like it, really. I don't think the rest of the world is even aware of it," he says.
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Sankt Nikolai almost perfectly intact
Stenberg has since taken many dives to inspect the sunken vessels more closely, but he isn't allowed near the jewel in the crown: the mighty Russian frigate known as the Sankt Nikolai. Discovered only in 1948 off of Kotka, the shipwreck was immediately protected by Finland's National Board of Antiquities because it was still virtually intact. Over 2,300 objects have already been retrieved from the hull of Sankt Nikolai by museum divers.
This part of the Baltic Sea has been a good resting place for the battle graveyard because the water has a low saline content and it is cold. The well-preserved vessels are nevertheless relatively close to the surface, at a depth of 20 metres, so they can be damaged by maritime traffic and ice.
Hundreds of sunken vessels
Finland's martime museum, Maritime Centre Vellamo, is located in Kotka, less than two-hours east of Helsinki. Opened in 2008, it has since won numerous awards, including steel structure of the year and top domestic travel destination of the year.
"The [Ruotsinsalmi] area is a one-of-a-kind site for maritime archeology. It is very large, with hundreds of wrecks. There aren't many naval battle graveyards on that scale or of that age left," says the museum's researcher Tiina Mertanen.
She says that a few war history and maritime archeology experts in Finland know about the strait, but the general public is still quite unaware of its importance.
"We've retrieved some wonderful material and stories. Now is the time to take advantage of what we have learned. If we can generate a local enthusiasm for what we have here, other people will begin to appreciate the site's cultural and historical significance," Mertanen says.
Vellamo exhibition set for 2020
Thomas Stenberg is one of 15 divers being trained to photograph and video the shipwrecks. His local diving club Kotka Divers will soon start capturing underwater images of the vessels in cooperation with the National Board of Antiquities. The video material will be used to construct 3D images of the sunken ships, which will be made available in the Board's database.
Efforts to make the site better known will begin in earnest in Finland in the coming years. An exhibition on the Battle of Svensksund and the warship graveyard found in Ruotsinsalmi is planned for the Maritime Centre Vellamo in 2020.