OLD ORCHARD BEACH, Maine — Dangerous rip currents at Maine and New Hampshire beaches led to dozens of rescues Monday at Old Orchard Beach and Hampton Beach.

Meanwhile, a number of Cape Cod beaches closed to swimming because of powerful and unpredictable rip currents.

“It was a busy day,” Old Orchard Beach lifeguard captain Keith Willett said Tuesday morning, as the lifeguards began to clear the beach due to rain, leaving only surfers riding rough waves.

Old Orchard Beach lifeguard patrols rescued three adults and seven children throughout the day Monday, on a mile-and-a-half stretch of the town’s four miles of beach, he said.

Single lifeguards were able to rescue nearly all of the swimmers, but at about 3:30 p.m., four guards headed into the surf to retrieve an 8-year-old girl and her uncle, who were struggling about 200 yards offshore.

Rip currents are narrow channels of fast-moving water — traveling as fast as eight feet per second — that move away from shore. They differ from riptides, which refer to the swift movement of tidal water through inlets, harbors and other coastal areas. Swimmers caught in rip currents are advised to swim parallel to shore and try to angle their route back to land.

“Usually the telltale sign is that the water is bubbling and you can see a long area where it’s all white, and that goes out past the surf, Willett said.

At Hampton Beach in New Hampshire, lifeguards helped bring 18 people to shore on Monday, WMUR-TV reported. People were only allowed to swim in waist-high water.

Most beaches that make up the Cape Cod National Seashore were closed to swimming on Monday due to rip currents and rough water, NECN reported.

Willett said Monday’s rip currents were the worst he’s seen this year, but it’s nothing compared to the summer of 2010, which was “10 times worse.”

The rescues followed a deadly weekend on Maine beaches. Early Saturday afternoon, 56-year-old Scott Ducott died while swimming off Pine Point Beach in Scarborough.

In Biddeford, two men became stranded on a sandbar at Hills Beach on Sunday and were rescued by another man in an inflatable boat, CBS 13 reported. One of the men, Jason Brawn, 46, of Westbrook remains in critical condition at Maine Medical Center.