Beaches along the south shore of the Island were closed to swimming as of early Thursday morning, as unusually large waves of the creatures continued to wash up.
Large swarms of Portuguese man o’ war jellyfish, a highly dangerous variety, have been discovered on the south shore of Chilmark this week, raising concerns over swimming safety.


Vineyard beach managers are reporting sightings of Portuguese man-of-war on south-facing beaches this month, with one report of a person stung.


Island waters have been invaded by Portuguese man-of-war in at least three towns in the past week, beach managers are reporting. The jellyfish-like creatures have washed up on beaches in Edgartown, Aquinnah and Chilmark, as well as in Westport, according to mainland news reports.

South Beach reopened to swimming Thursday after several Portuguese man-of-war stings forced the town to close the beach to swimming on July 3. “They are dangerous, they are prolific,” said Edgartown parks administrator Marilyn Wortman Wednesday morning, just hours after two lifeguards were stung and sent to the hospital. “Don’t go in,” she said, “you’re going to get stung.”

South-facing beaches along Martha’s Vineyard are under high risk for rip currents today, the National Weather Service has announced. The warning will remain in effect through Monday evening.

In response to the warning, The Trustees of Reservations has closed the beach at Long Point Wildlife Refuge. Swimmers are encouraged to use the pond for swimming.