A Shanghai tourist was rescued by a fishing boat after she fell 20 metres off Royal Caribbean’s Mariner of the Seas.

The ship was returning from Japan to Shanghai when the 31-year-old woman fell from the ship when the vessel was approaching Shanghai’s Wusong Port.

After a heart-rending search by her parents and 100 volunteers, the line told her father they thought she was dead.

Two days later, a telephone caller told them she had been saved by a fishing board.

“Only after I heard my daughter’s voice did I believe she was still alive. It’s a miracle,” the father said, adding that his daughter was a strong swimmer.

He claimed she had managed to stay afloat even after falling asleep.

The woman, surnamed Fan, was travelling from Fukuoka to Shanghai when she was reported missing at around 9pm on August 10. She was picked up by the fishing vessel at around noon on August 12.

Reports have revealed that she continued to tread water even while she was sleeping.

Ms Fan was interviewed and told rescuers she was a strong swimmer because she attended a sports university.

Her parents told a local Chinese newspaper that she had not eaten or drank anything during the ordeal, but  survived because of her “strong willpower”.

Ms Fan managed to stay awake and remain afloat without anything to hang onto and had to swim away from big ships to avoid their propeller blades.

Crew members said Ms Fan was found swimming in jellyfish-infested waters and had a number stings on her. She was otherwise unharmed.