Seven people have been rescued after writing a message in sand calling for help.
The four adults and three children had sailed to a beach in Cornwall but were trapped by a 2m (6ft) onshore swell on Tuesday, the RNLI said.
They wrote "send for help" in the sand, which was spotted by a cliff-top walker who called emergency services.
The RNLI's inshore lifeboat at Rock got them off the beach and transferred them to other vessels to be taken ashore.
The party had travelled around Stepper Point to a beach at Butter Hole in a sailing dinghy and a small rigid inflatable boat (RIB) for a picnic, the RNLI said.
After the swell started, the adults were afraid to launch back into the sea with the children on board.
They wrote their message in the sand because they had no VHF radio and no mobile phone reception, the charity said.
The Rock lifeboat was launched at about 15:20 BST.
The Padstow coastguard team and the Padstow all-weather lifeboat were also called out.
The inshore lifeboat transferred the rescued party to a nearby tripping boat, the Ocean Voyager, and the all-weather lifeboat.
The RNLI volunteer lifeboat operations manager at Rock, Mike Hewitt, said the group made a "very sensible decision" not to launch their boats to return but were lucky the passing walker saw the message.
He said: "I would remind people that it's important to have a suitable means of contacting someone when going to sea.
"Don't assume you will have a mobile phone signal when you go to a beach by water, so take a VHF radio."