A 19-year-old man was 'escorted to safety' after being seen in the sea opposite Blackpool Tower in the early hours of this morning, the RNLI said.
Volunteers from the resort's Promenade lifeboat station were scrambled at around 2.30am and found the man as they were preparing to launch its two lifeboats, the charity said.
"Our volunteer crew members escorted the casualty to safety along with a crew from the North West Ambulance Service," a spokesman added.
The Coastguard at Lytham was also called out at around 2.40am, but rescuers were stood down when they arrived at the scene to find the man in the back of an ambulance.
A spokesman said the 19-year-old had been detained by police and was being checked over by paramedics.
It is understood the man was found close to Central Pier, several hundred yards from where he was first spotted.
The rescue effort came just days after a man's body was pulled from the water just south of North Pier.
The young man, named locally as Michael Buckley, was later described by friends as a 'great guy' and a 'good friend'.
Mr Buckley's death was not being treated as suspicious, police said, and a coroner was expected to open an inquest into the circumstances surrounding it.
A number of bodies have been found on Fylde coast beaches or pulled from the sea in recent months, including that of a middle-aged man in Cleveleys last month, that of a man in his 40s, also in Cleveleys, in October, and that of a man in his 60s near to Central Pier in Blackpool in September.
There have been five deaths in similar circumstances this year, the Coastguard said, slightly higher than the yearly average.
None were deemed suspicious by police.