An elderly woman swimming in the ocean off Manhattan Beach in Brooklyn was clinging to life yesterday after lifeguards pulled her out of the water, authorities said.

Yevgenya Shyknevskaya, 85, was spotted floating off the beach 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 lifeguards grabbed her, brought her in and started CPR.

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

Shyknevskaya was rushed to Coney Island Hospital, where she was in critical condition.