Environmental campaigners say they are outraged by news of an increase in the amount of dredged material that can be dumped off Whitsand Bay in Cornwall.
The bay is a famous South West beauty spot
The Ministry of Defence (MoD) has been given permission for a four-fold increase by Department for Environment, Food and Rural Affairs (Defra).
The new licence means 201,527 tonnes of material can now be dumped at the beauty spot, up from 50,533 tonnes.
Defra said it had a detailed assessment and the site would be monitored.
The tonnage is equivalent to the displacement of 40 Type-23 frigates.
South East Cornwall Liberal Democrat MP Colin Breed said: "It's quite obvious the bay is overfull. This site needs to be closed.
"It certainly does not need another 200,000 tonnes of material."
Defra said it issued the licence after a detailed assessment by marine scientists and close consultation with the Environment Agency and English Nature. It said the site would continue to be monitored.