Three children and a man in an inflatable toy dinghy have been rescued by a lifeboat crew 500m out to sea, the RNLI said.
The group, all in swimwear and none wearing lifejackets, was spotted off Kinmel Bay, Conwy.
Rhyl beach lifeguards saw the man trying to row ashore against the wind and tide on Wednesday afternoon.
The RNLI said coastguards later told the man, who was unaware of the dangers, about the risks to the group.
The rescue charity said the incident with the toy dinghy was the "most potentially dangerous rescue" of the day.
A spokesperson said: "The children were starting to look cold so they were all taken on to the lifeboat, and taken back to the shore where the children's' family were waiting.
"The adult was unaware of the danger he had put the children in, but was educated by local coastguards on his return to the shore."
The RNLI said the rescue was one of five launches by Rhyl's lifeboat crew between 1300 BST and 1800 BST on Wednesday.
In a statement, it said: "There was an ebbing tide and an offshore breeze, which caught many holidaymakers unawares.
"As well as searching for missing children, the crew also had to recover abandoned inflatable dinghies, or escort people in dinghies ashore."