Two people and their dogs found themselves marooned on small rocks a mile from the shoreline as the tide raced in around them.
They appeared to be standing on the water in a photograph released by the RNLI after a rescue near Little Eye island, near West Kirby, at about 12:15 BST.
The rescue charity said the dog walkers had checked tide times before setting out on the popular walking route to the island, but had misunderstood them.
A spokesman said a lifeboat returned the people and their dogs to shore safely.
