Parents have been told to ‘exercise caution’ with their children at the new seafront lagoon after a mysterious green substance was seen floating on the edge.

Our photographer was at the scene earlier today, amid a number of screaming children and OUTRAGED parents. 

Southend Dad Alan Gee was visiting the lagoon with his two children, and he blasted council bosses for letting the green ‘sludge’ build up. 

He said: ‘My eldest son is in hospital this evening after eating some of the green stuff down there – I feel partially responsible for encouraging him to eat his greens.’

‘He was ok at first, but after a few minutes he just went wide-eyed and just kept running around in circles while demanding something called a Krabby Patty. How dare the council let it get this bad.’

Southend Borough Council’s in-house marine biologist Henrietta Clench told Southend News Network that there is no need for any alarm. 

She said: ‘Some samples have been sent to a lab for analysis, and we should have some concrete information within six weeks.’

‘Until then, there is no reason why parents shouldn’t bring their children to the new lagoon. If paddling, it is relatively quick to cover their legs in cling film to be extra-safe.’

A social media campaign has already been started to raise awareness of the problem.