Firefighters were called to two teenage boys stuck in mud at Wat Tyler Country Park at 15:28 on Saturday.
The fire service worked with the coastguard, police helicopter and the RNLI and located the boys. Crews had rescued the boys from the mud by 17:28.
Assistant Divisional Officer Paul Chipperfield said: “The two boys aged 15 and 16 years old were taking a short cut home across a muddy creek when they became stranded up to their waist in mud. There were three boys in total and the third friend was not stuck in the mud.
“It was difficult to locate the boys from the land, so the police helicopter was called in to search for them, once they were located at Marsh Farm, Pitsea Hall Lane, which is adjacent to Watt Tyler Country Park, the rescue operations could begin.
“The ECFRS swift water rescue team from Leigh used their sled and rescue paths to reach the boys, the RNLI used their hovercraft, and crews worked together to rescue the lads who were about 20 foot from the land. The pair were suffering from shock and the cold, and were placed in the care of the Ambulance Service.
“Thanks to the efforts of everyone involved in the rescue and the successful outcome, by bringing the boys to safety.
ADO Chipperfield added: “ECFRS is urging all young people to take care near open water, incidents like this show how dangerous it is to wade out into muddy waters and how easy and quickly it is to become trapped and out of your depth.”