As the heatwave continues, Tower Hamlets council has urged people not to swim at Shadwell Basin.
The East London dock has been used for industrial purposes, and the local authority says there are a number of dangerous hazards under the water.
It's ordered new measures to secure the area, including:
• New CCTV and warning signage installed.
• Swimmers encouraged to use Tower Hamlets swimming pools
• Tower Hamlets enforcement officer patrols stepped up
It comes following footage of a young man jumping into the basin from a bridge, and reports of other swimmers getting into difficulty in the last week.
Tower Hamlets' Mayor John Biggs said: "It's just over two years to the day when we tragically lost a young man who drowned at Shadwell Basin and I do not want a repeat of the tragic loss of life. I appeal for swimmers to stay away from the dangerous open water at Shadwell Basin which is not safe to swim in. Just 250 meters away from the basin we have a fantastic pool at St George's baths and I urge people to swim there safely."