A crowd stood and watched an elderly couple struggling waist deep in water at West Kirby Marine Lake without raising the alarm.
Details of the incident have been revealed by West Kirby RNLI, which says it happened during the storms and high tides last week.
The pair were only rescued when two off-duty RNLI volunteers arrived and saw what the crowd were observing.
They called 999 and informed the Coastguard before heading into the water to rescue them.
In a post on their Facebook page, West Kirby RNLI said: “During the storms and high tides last week an elderly couple were seen struggling waist deep in water walking round the Marine Lake.
“They had been watched for sometime by a significant crowd before off-duty West Kirby Lifeboatman Mike Warburton and RNLI Lifeguard Richard Webster arrived and saw what the crowd were observing.
“They immediately phoned 999, informed the Coastguard of the situation and then without hesitation waded out to guide the couple ashore.
“Once safely on dry land they checked the couple were okay and informed the Coastguard of their safe return.”
The RNLI is urging people to call always 999 and ask for the Coastguard if they see someone in difficulty.
They say if the water rises above the lake wall people should immediately turn back, even if it means not following the recently introduced one-way system.