The Ostseezeitung reported on Thrusday that there had been several recent sightings of the animal, which is thought to be about 12 metres long and has been given the less-than-inspired nickname of "Bucki" in a play off "Buckelwal," the German word for humpback, and which translates to "Humpy."
Holidaymakers spotted it near Warnemünde, right up by the coast on Tuesday, while a day later it was seen by guests at a wedding in Sellin on the island Rügen.
Greenpeace biologist Jörg Feddern says the animal could easily cover 150 kilometres in a day, and said it was unlikely that two humpback whales would be in the area.
Klaus Harder, of the Stralsund marine museum said the crew of a ship had also spotted it in the waters between Germany and Denmark.
“We hope that the animal quickly finds its way back into the Atlantic,” he said, adding its stay in the coastal waters will cost the whale dearly in energy, using up its fat stores quickly, depending on how much it can find to eat.
Humpbacks are baleen whales – filtering their food from the water, they eat small fish and krill, and can swallow more than 1,300 kilos a day.