A passenger reported missing from Carnival Valor was found alive by the US Coast Guard several hours later.
The man had last been seen by his sister at 11pm on Wednesday evening, when he left a bar to find a restroom.
His sister said he never returned to his cabin and she reported him missing at noon yesterday, as the ship was sailing towards Cozumel.
Coast guards were alerted at around 2.30pm and Carnival Valor retraced its route to support the search and rescue in the Gulf of Mexico, said CNN.
The man was spotted in the water by crew on another vessel and pulled from the sea by helicopter.
He is said to have been responsive at the time of rescue and was transferred for emergency medical treatment at New Orleans airport.
Carnival Valor then continued to Cozumel, where it is due to arrive five hours late. It is sailing a five-night Western Caribbean cruise, having left New Orleans on Wednesday.