The incident occurred when the Royal Caribbean ship Odyssey of the Seas was sailing southwest of the island of Zakynthos, the Greek coastguard said.
A woman who allegedly jumped off a cruise ship into the Ionian Sea was rescued over the weekend after 20 hours in the water, the Greek coastguard said.
The incident occurred early on Friday when the Royal Caribbean Cruises ship Odyssey of the Seas was sailing southwest of the island of Zakynthos, the coastguard said.
The 44-year-old Salvadorian woman subsequently told her rescuers she had jumped because "she wanted to disembark," a coastguard spokesperson told AFP.
After an alert went out early on Friday, two coastguard boats and a navy helicopter were dispatched to the area and other nearby ships were rerouted.
The Odyssey of the Seas also joined the search, the officer said.
A passing freighter eventually located the woman, fully conscious, in a life ring early on Saturday and she was picked up by a Greek coastguard patrol boat.
A video released by the coastguard shows a crew throwing a rope to a woman floating inside an orange life ring in the water in the dark.
She was taken to the port of Katakolo and then to hospital in the nearby city of Pyrgos for health tests that include a psychiatric evaluation ordered by a local prosecutor, the coastguard officer said.
According to Royal Caribbean, Odyssey of the Seas is 1,138 feet long and can accommodate 4,198 guests. The ship offers seasonal cruises to the Greek Isles.
Last year, a man jumped off a Royal Caribbean cruise ship near the Port of San Juan — allegedly to avoid paying off more than $16,000 in gambling debt to the cruise line. Jey Gonzalez-Diaz allegedly jumped into the water as the ship disembarked, during U.S. Customs and Border Protection inspection, according to a criminal complaint. He was then brought to shore by someone passing by on a jet ski, and later charged with attempting to avoid monetary reporting requirements when traveling into the U.S.