Three young people entered the sea overnight near to North Pier, says the Coastguard.
Blackpool RNLI and a coastguard rescue team were called out to the incident at around 12.30am on Friday, April 27 by police.
The children, who were missing from care, waded out into the water near to the Metropole Hotel.
A spokesman for the Coastguard said: "We were called to three youths in the water.
"They had gone in up to their knees but sat down in the water which made it look like they were in much deeper.
"We sent a man in on a rope to talk to them and the RNLI lifeboat was also called out.
"They were brought out of the water safe and well."
The incident is not believed to have been a suicide bid.