Divers are being warned that a fishing net has blocked part of an artificial reef off the coast of Cornwall.
Former Royal Navy frigate HMS Scylla was sunk in Whitsand Bay in 2004 to create the reef.
A monofilament gill-net was discovered on the wreck on Friday, Falmouth Coastguard said.
The National Marine Aquarium in Plymouth, which oversees the wreck, said it would try to remove the net on Saturday.
It was not known whether the net was placed there, or whether it drifted from a fishing vessel, coastguards said.
Divers have been urged to take extra care.