Authorities in Spain have called off the search for free diver Natalia Molchanova on Wednesday as fears grow that she could be dead.

The Associated Press reported that the underwater search was called off after rescuers spent more than two days trying to locate her.

Molchanova’s family and the international diving federation AIDA, said in statement that the 53-year-old Russian did not resurface after a dive off the coast of Formentera island on Sunday.

"The cause of Natalia's disappearance is unknown, but she was doing what she loved. Natalia has a passion for free diving that burned so deep inside of her that she dedicated her life to it," the statement read.

After the days-long extensive search the possibility of Molchanova being found alive is becoming less likely. Her family believes that she may have gotten caught in a strong underwater current and was then separated from her peers.

The free diver is regarded as the best in the world and has set 41 world records with claim 23 world championship titles.

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