A student who has been missing since Boxing Day left a note outlining her intention to take her own life by going into the sea, police have said.
Sophie Smith, 21, had been suffering severe anxiety and depression and had been receiving treatment for her mental health, Norfolk Police said.
The last sighting of her was on CCTV running towards the seafront in Gorleston after she left her home.
Ms Smith's mother said she and her family "fear the worst".
"In our hearts we hold every hope she will return safe and well," Lynn Shaw said.
"However, as a family, knowing the troubles she was experiencing, we do fear the worst for our little girl."
Detectives have carried out "comprehensive inquiries since her disappearance", the force said in a statement.
Aside from the CCTV footage "all other inquiries... have been negative", police added.
Mrs Shaw said she urged anyone who was experiencing anxiety or depression "not to fight that battle alone and seek help".