Coastguard officials said they were "seriously dismayed" by tourists who ignored signs and prompted a rescue from a Northumberland causeway.
The Seahouses Inshore Lifeboat was diverted to Holy Island Causeway on Wednesday to rescue a couple in a camper van.
The pair, from Nottingham, ignored crossing times to the island, which is cut off by tides twice every 24 hours.
A coastguard spokesman said the couple could have lost their lives.
The man and woman abandoned their vehicle and made their way to a refuge box, calling for help on the emergency telephone.
The lifeboat crew, which was on its way to visit a local school, was paged and diverted to the causeway.
Ian Clayton, lifeboat operations manager, said: "I am seriously dismayed, that despite the clear signage and all the publicity, we are still being called to rescue people from the causeway.
"I remain concerned that on a really big tide, there could be a loss of life when people act with such disregard for their own safety.
"They showed a total lack of appreciation that they were driving into the North Sea, not crossing a country ford or stream."