An older female swimmer is clinging to life after lifeguards pulled her out of the waters off Manhattan Beach in Brooklyn today, authorities said.

The woman, who was in a bathing suit, was spotted floating in the water at 2:20 p.m. by a lifeguard, police said.

“I heard the guard blow the whistle, and I just saw this old lady floating in the water,” said witness Asad Butt, 22.

He said he tried to swim over and get her but that lifeguards grabbed her, brought her in and started CPR.

“They worked on her for a long time, maybe a half-hour of so, but she wasn’t showing any signs of life,” said bystander Susan Aurichio.

The victim was rushed to Coney Island Hospital, where she is in critical condition, authorities said.