People who drive off-road on Somerset's Quantock Hills are being warned to stay legal or face big fines. Police and rangers say they are patrolling the area looking for people illegally driving around the tracks.
The Quantocks have been designated a Site of Special Scientific Interest and police have enhanced powers to protect the hills from damage.
They warn anyone caught breaking the law could be fined up to �20,000 and have their vehicle confiscated.
Drivers are being told to stick to designated rights of way and to make sure their vehicles have an up-to-date MOT certificate, tax and insurance.
A recent survey among people who walk on the hills said off-roaders were their biggest concern, saying they felt annoyed and intimidated by them.