"The Baltic sea's cool, brackish waters have for centuries protected the wrecks from the wormlike mollusks commonly called 'termites of the sea'. But now global warming is making the Baltic Sea more comfortable for the critters. Shipworms, which can obliterate a wreck in ten years, have already attacked about a hundred sunken vessels dating back to the 13th century in Baltic waters off Germany, Denmark, and Sweden."
"Until recently the wood-boring mollusks, which generally require relatively salty waters, were unable to survive in the low-salt Baltic. In warmer water the animals appear to be somehow 'less stressed' by low salinity."
It should be noted that "the Baltic holds about a hundred thousand well-preserved shipwrecks—and counting. Really nice tall ships with the mast and everything intact are still being discovered. Every time [researchers] go down there with remotely operated vehicles they find new wrecks."