This article was featured in Eurofish Magazine 5 2026.
An unusual warm-water marine visitor has been recorded along Denmark’s North Sea coast, where several by-the-wind sailors (Velella velella) have washed ashore. The small, blue organisms normally occur in warmer parts of the world’s oceans, including the Mediterranean, and are only rarely reported in Danish waters. By-the-wind sailors live at the sea surface and have a flat, dark-blue floating disc topped by a small sail. They generally grow to around 5–7 cm and are carried largely by wind and surface currents rather than active swimming. Marine specialists believe particular wind and current conditions are likely to have transported the animals unusually far north.
Several specimens were reported along the north-western Danish coast in early August. Despite their striking appearance, the organisms are not considered dangerous to people and do not sting in the same way as some jellyfish. Direct contact can, however, cause mild itching or skin irritation.
