The incident happened at Unity Farm Caravan Park, Coast Road, Burnham-on-Sea.
Firefighters from Burnham found the casualty trapped about five feet below ground level. They removed part of of hedge for access and rescued the person using a ladder lowered down the bank.
A specialist water rescue team from Chippenham were also called to the scene in case they were needed.
An ambulance attended to check the casualty for injury.