A spokesman for Norfolk Police said:
"The man was retrieved from the water and was taken to Addenbrooke's Hospital by air ambulance for treatment. He is currently described as being in a critical condition.
"Police and the Health and Safety Executive are carrying out a joint investigation into the incident."
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Low cloud and mist developing overnight. Another mild night ahead. Generally rather cloudy tomorrow, with a few brighter breaks developing.
Generally cloudy with occasional outbreaks of rain during the morning. Some glimpses of the sun are possible. Feeling mild