The man, Jonathan Pender, told The New York Post, “I had him in my hands.” But Joshua “was panicking and he went back under.”

Investigators said they recovered Joshua’s body on Monday afternoon.

Later, a family friend, Sherell Footman, told the paper, “The seaweed wrapped around his leg and pulled him down.”

Just days before, on July 31, the body of John Munoz, 18, was found near a Rockaway Beach jetty.

“He was playing and I guess he slipped and the tide came and took him away,” Mr. Munoz’s sister, Yesenia Rodriguez, told The Daily News, adding that the p olice “got there about five minutes later, but they weren’t able to get him.”

On July 9, a Long Island couple, Umarie Chamble and Keylon Ramsay , drowned after celebrating a friend’s birthday near Beach Ninth Street and Seagirt Boulevard.

“Her boyfriend, Keylon, doesn’t know how to swim, and she was trying to teach him and that’s when it happened,” Ms. Chamble’s cousin told The Daily News.

The couple had gone into the water shortly after 10 p.m.

All four deaths were on or near the east side of the Rockaway Peninsula, Mr. Richards, the city councilman, said.

Crystal Howard, a spokeswoman for the parks department, said, “We are saddened by these unfortunate deaths. We want everyone to be safe and implore New Yorkers to only go swimming in designated waters during operational hours, when lifeguards are on duty.”