Eight people had to be rescued off the coast of Wirral including a family-of-five who were chest deep in water after being cut off by the rising tide.
Lifeboat crews said they found the father struggling to keep his five-year-old daughter's head above water on Hilbre Islands on Tuesday.
West Kirby RNLI brought all the stranded walkers to safety with some needing treatment due to hypothermia.
The rescue has prompted warnings over the dangers by lifeboat crews.
"Getting cut off by the tide can be a frightening experience," said Richard Diamond, West Kirby RNLI lifeboat operations manager.
"We would remind visitors to Hilbre to check the tidal information before setting out and to take appropriate clothing."
The islands are surrounded by the tide for up to six hours twice a day but crossing the sands from West Kirby is popular with walkers and bird-watchers.
West Kirby RNLI was alerted by HM Coastguard at 13:30 BST that a woman and her dog had become cut off by the incoming tide on one of the islands known as Middle Eye.
She had also noticed a family-of-five who "were highly distressed and required immediate assistance" along a ridge of rocks to the south of Middle Eye.
The family were not aware they were in a tidal location, the West Kirby RNLI said.
Further along the ridge of rocks was a couple who were "soaking wet due to immersion in the flooding tide and cold from the increasing wind".
Mr Diamond urged the public to dial 999 and ask for the Coastguard if they spot anyone in trouble.