Police have warned swimmers not to take a dip in a "notoriously dangerous" former quarry near Halesworth after people were seen cooling off in the water in the recent warm weather.
Officers have been called out to Holton Pit, east of the town, after receiving reports of swimmers - including children - in the water as temperatures have reached close to 30C.
The pit is a site of scientific special interest and is used by members of Woodbridge and District Angling Club for fishing.
But Halesworth police said on social media that officers had been made aware of residents' concerns of youngsters in the water in recent weeks.
Police said in a statement: "Due to the hot weather, we've had reports of young people swimming in the fishing lake on site.
"Quarries are notoriously dangerous places to swim due to the depth of the water, meaning it remains very cold and can shock the body into a fatal cold response."
The warning comes after several people have died while swimming in the water at Bawsey Pits - another former quarry - near King's Lynn in Norfolk over the last decade.
Swimming at the beauty spot is banned due to cold shock and signs are in place warning visitors not to dip in the water.
Only last week, a man in his 20s had to be pulled from the pit and taken to hospital after emergency crews became concerned for his safety.
Suffolk Fire and Rescue Service, which is responsible for water safety advice in the county, has also urged people not to cool off in the pit at Holton in warm weather.
A spokesman for the service said: "Even the strongest swimmers can get into serious difficulties in open water.
"These types of open water can be incredibly deep in places, but very shallow in others - particularly when the water levels drop over the summer. This makes jumping into the water extremely dangerous.
"Even in a heatwave, the water temperature stays very low. It’s so cold it can cause shock or hypothermia. Plus the water hides other dangers such as machinery, sudden dips and drops, weeds and mud, and very strong currents created by the changing depths."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here