The 28-year-old man had been at a bar on the Carnival Valor ship with his sister on Wednesday night but did not return after leaving to use the toilet.

Several rescue crews scoured the area and the man was finally spotted on Thursday evening, some 20 miles (30km) off the coast of Louisiana.

He is said to be in stable condition.

Lt. Seth Gross of the US Coast Guard said the man could have been in the water for more than 15 hours — the “absolute longest that I’ve heard about — and just one of those Thanksgiving miracles”.

Gross told CNN that the case was unlike anything he had seen in his 17-year career and that the happy outcome “shows the will to live is something that you need to account for in every search-and-rescue case”.

It is unclear how the man came to plunge into the water from the ship, which was en route to Cotumel in Mexico.

In 2018, a 46-year-old British woman was rescued 10 hours after falling into the Adriatic Sea from her cruise ship.

At the time, she was reported to have told one rescuer it had helped that she was fit from doing yoga and that she sang to stop her feeling cold overnight.