Beach patrols near North Pier were forced to warn teenagers to move away from danger after they were spotted close to the water's edge.
The patrols, who are operated by Blackpool Council, spotted the teenagers at around 4pm on Sunday September 24 on the Gynn slipway.
The teens are reported to have been around 16-17 years old and moved away after their initial warning but were spotted back in the same place minutes later, a representative for Blackpool council confirmed.
The spokesman for the council said: "Beach Patrols spotted the teens close to the water's edge and warned them about dangers of the sea. The tide was in and they were in a particularly dangerous situation.
"Ten minutes later beach patrols sighted them again taking their tops off as if they were planning to go swimming.
"The beach patrol warned them again, this time using their siren and tannoy to highlight to them the dangers of what they were planning to do.
"Patrols spoke to them about the risk they posed, not only to themselves, but also to others who would have to go into the sea to rescue them.
"The tide was in and the water was deep and the temperature would have been dropping.
"They were given a severe warning about the dangers of the sea and their activities.
"The sea can be particularly dangerous and due care should always be taken when close to the water's edge."
A Blackpool council spokesman said that the teens were advised that if they did not move away from the area, police would be informed.
Nobody was injured during the incident.
If you see somebody in trouble in the sea dial 999 and ask for the Coastguard.