<strong>"Ghost ships": </strong>In the icy waters surrounding Scandinavia, divers Jonas Dahm and Carl Douglas explore and photograph wrecks long lost to the ocean, the so-called "ghost ships'' of the Baltic Sea. This picture is of an unidentified shipwreck dating possibly from the 17th or 18th centuries.
"Ghost ships": In the icy waters surrounding Scandinavia, divers Jonas Dahm and Carl Douglas explore and photograph wrecks long lost to the ocean, the so-called "ghost ships'' of the Baltic Sea. This picture is of an unidentified shipwreck dating possibly from the 17th or 18th centuries.
Jonas Dahm
<strong>Underwater photography: </strong>On dives, Dahm captures haunting photographs, including this one of an unidentified Russian submarine from the First World War. Dahm and Douglas also extensively research the wrecks they explore.
Underwater photography: On dives, Dahm captures haunting photographs, including this one of an unidentified Russian submarine from the First World War. Dahm and Douglas also extensively research the wrecks they explore.
Jonas Dahm
<strong>Photos and reflections: </strong>A selection of Dahm's photographs, paired with Douglas' written reflections, feature in the book "Ghost Ships of the Baltic Sea," published by Swedish publisher Bokförlaget Max Ström. This chronometer, a type of clock, was photographed on the German steamer Otto Cords which sunk in the Second World War.
Photos and reflections: A selection of Dahm's photographs, paired with Douglas' written reflections, feature in the book "Ghost Ships of the Baltic Sea," published by Swedish publisher Bokförlaget Max Ström. This chronometer, a type of clock, was photographed on the German steamer Otto Cords which sunk in the Second World War.
Jonas Dahm
<strong>"History coming to life": </strong>This photograph is of Svärdet, a Swedish navy war ship which sank in 1676. Bronze cannons can still be seen on and around the wreck. "Diving around Svärdet was one of the greatest underwater experiences of my life," writes Douglas in the book. "I had an overwhelming sense of history coming to life."
"History coming to life": This photograph is of Svärdet, a Swedish navy war ship which sank in 1676. Bronze cannons can still be seen on and around the wreck. "Diving around Svärdet was one of the greatest underwater experiences of my life," writes Douglas in the book. "I had an overwhelming sense of history coming to life."
Jonas Dahm
<strong>Interior shot:</strong> Dahm took this picture of the interior of what was once a passenger cabin on board the Aachen, a 19th century steam ship that sank in the First World War after becoming a German navy vessel.
Interior shot: Dahm took this picture of the interior of what was once a passenger cabin on board the Aachen, a 19th century steam ship that sank in the First World War after becoming a German navy vessel.
Jonas Dahm
<strong>Light and dark:</strong> Dahm says there are many challenges associated with photographing wrecks -- from lighting to visibility. Plus, many of the ships are some 100 meters under the sea. Pictured here: remnants of the steam ship Rumina.
Light and dark: Dahm says there are many challenges associated with photographing wrecks -- from lighting to visibility. Plus, many of the ships are some 100 meters under the sea. Pictured here: remnants of the steam ship Rumina.
Jonas Dahm
<strong>Capturing atmosphere:</strong> Dahm and Douglas and their team of divers use flashlights to illuminate details for the photos. They also try to capture the atmosphere of the murky waters. Pictured here: the SMS Prinz Adalbert, another German ship that sank during the First World War. The ship was broken in two, and this picture depicts what remains of the ship's stern.
Capturing atmosphere: Dahm and Douglas and their team of divers use flashlights to illuminate details for the photos. They also try to capture the atmosphere of the murky waters. Pictured here: the SMS Prinz Adalbert, another German ship that sank during the First World War. The ship was broken in two, and this picture depicts what remains of the ship's stern.
Jonas Dahm
<strong>Capturing details:</strong> The 19th century steamer Astrid is in "poor condition," writes Douglas, but its figurehead remains intact.
Capturing details: The 19th century steamer Astrid is in "poor condition," writes Douglas, but its figurehead remains intact.
Jonas Dahm
<strong>Marine life: </strong>This photograph shows a cod swimming past the wreck of SMS Undine, a German cruiser that became a naval ship during the First World War.
Marine life: This photograph shows a cod swimming past the wreck of SMS Undine, a German cruiser that became a naval ship during the First World War.
Jonas Dahm
<strong>Unknown stories: </strong>The ship Liro was built in 1876, and sank in 1931. Why Liro sunk remains unknown. For Dahm and Douglas, such mysteries are always intriguing. "I will probably never know the answers to all these questions, but it's okay, most shipwrecks will never reveal their secrets anyway," Dahm tells CNN Travel.
Unknown stories: The ship Liro was built in 1876, and sank in 1931. Why Liro sunk remains unknown. For Dahm and Douglas, such mysteries are always intriguing. "I will probably never know the answers to all these questions, but it's okay, most shipwrecks will never reveal their secrets anyway," Dahm tells CNN Travel.
Jonas Dahm