Her son, Alexey Molchanov said on Tuesday afternoon that his mother, 53, was not expected to be found alive and Maritime rescue services told The Local that it could be days before her body is discovered, if at all.
The 53-year-old Russian who held 41 world records in freediving and could hold her breath for nine minutes, was diving to a planned depth of 35 meters (115 ft) in waters two miles northwest of the port of La Savina at Poniente de es Freus on Sunday.
Miguel Felix, the head of the Balearic Islands Salvamento Marítimo who led the initial search for Molchanova described the circumstances of her disappearance.
"Those with her saw her going down but they didn't see her coming back up again," he said of the recreational dive she made with her son and friends from a chartered boat on Sunday afternoon.
"After 15 minutes the alarm was raised and we sent out boats and a helicopter to look for her but with there was no trace of her on the surface," Felix told The Local by telephone.
He admitted that her body may never be washed up. "She was wearing weights to stop her floating to the surface – which is usual for the purpose of a dive – but it means that instead of floating up her body could be taken to the depths."
The rescue chief confirmed that although the official search had been called off, the family had privately hired a diving robot to make an extensive search of the underwater area in the hope of recovering her body.
"We are experts in search and rescue on the surface of the sea," he said of the Salvamento Marítimo. "But we have no expertise when it comes to the depths below."
The family explained that the world champion, who in May set a record of 71 meters (233 feet) for a dive without oxygen, may have struggled with strong underwater currents or a sudden plunge in water temperature.
"She was diving without fins to around 30 to 40m and supposable (sic) got into strong underwater current," a statement released by her family said.
She was the world's most decorated free-diver of all time, having amassed 20 individual gold medals and two team gold medals from the Free-diving World Championships.
The world lost its greatest freediver on Sunday, and my friend Alexey lost his dear mother, teacher, and training... http://t.co/5jmgHCt3YU— William Trubridge (@WillTrubridge) August 4, 2015
Her family praised her as "an inspiration" who died "doing what she loved".
"Natalia is a proud mother of Oksana and Alexey. She loved children and was awaiting the day when she would become a Grandmother," said the statement posted on the Facebook page of AIDA International, the international body that regulates the sport of free-diving.
"She was an inspiration to all freedivers and despite being one of the fiercest competitors in the world, she was always calm and relaxed during competitions," the statement continued.
"She said 'birth and death are important, but freediving competitions are just games for adults'."
The statement added: "The cause of Natalia's disappearance is unknown, but she was doing what she loved. Natalia has a passion for freediving that burned so deep inside of her that she dedicated her life to it."