At 90 feet, Cliff Pond is the deepest pond on Cape Cod. It's located in Nickerson State Park, and is a popular for swimming and boating.
two dogs* that had been swimming in the pond.
Closures of the pond to swimming have increased in recent years. Last year, park officials closed the pond for a total of 99 days. This summer, the pond was closed from June 25 to July 9.
The reason was high levels of blue-green algae.