Their bodies were pulled from the water just hours later on Friday night and on Monday, their loved ones spoke out about the tragedy.
"They are not beachgoers at all, they've never been, never," said their father Mohammed Ahmed Faye.
Friday was an exception -- Aisha and Zainab Mohammed made a game-day decision to leave the Bronx to celebrate a cousin's birthday on the beach at Coney Island.
"When they were young, we go to Coney Island, but they never swim. Never. They even took steps in the water, they don't walk. They were afraid," Ahmed Faye said.
Their father said he was unaware his 17 and 18-year-old daughters had even left the borough.
On Friday evening around 8 p.m., near Stillwell Avenue and the boardwalk, witnesses say the sisters were enjoying the ocean and got out during a downpour, but decided to wade back in - even though they were cautioned not to.
"One of the boys tried to rescue them, but he couldn't, the current was so strong, and he couldn't," Ahmed Faye said.
Lifeguards at New York City beaches are only on-duty until 6 p.m. each night. After that, heading into the water could be dangerous.
"It's a tragedy that happened but they should be careful, swimming out there especially when there are no lifeguards around," said beachgoer Mel Freedman. "That is what we're seeing not only with the two girls, but with other people."
Two weeks ago, two teenage boys drowned at Riis Beach at Jacob Riis Park while swimming after hours.
"It's the heat and maybe even the cost of going on the beach, because they don't have the money, so they come after the lifeguards are gone," Freedman said.
On Monday, some beachgoers said they couldn't get the tragedy of the sisters off their minds.
"I thought about it yesterday, I came here again, it's scary to go in the water, you never know what happens," said beachgoer Edna Drici.
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Queens leaders call for new swim safety measures amid more drownings
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