The victim, aged in her 30s, was allegedly assaulted on Towan Beach, Newquay, Cornwall, UK.
Devon and Cornwall Police have said the reported attack happened on Sunday March 1 at around 4:00 am.
A 38-year-old man from the arrea has been arrested on suspicion of rape.
He has since been released on bail, according to the force.
Police have said they believe someone who was fishing on the beach near the time of the alleged attack may know key details.
Detective Inspector Chris Donald said: “Our inquiries remain ongoing in relation to this case and we are really keen to identify and speak to a person who may have seen or heard something which may assist our inquiries.”
“Through CCTV inquiries we believe a person was fishing on the beach in the early hours of Saturday and I would ask them to get in touch with us.”
“I’d also ask that anyone else who was in the area and may have relevant information, to please get in touch.”
This comes after tragedy has struck at Towan Beach in recent years.
In 2017 a man mysteriously lost his life on the cliffs on a night out with some friends.
The devoted dad fell to his death following his first night out after being given the “miracle” all clear from cancer three weeks earlier.
Adam Fenton, 31, was discovered at the foot of cliffs on Newquay’s Towan beach after he failed to return from his first night to the pub with pals since receiving the good news.
The roofer had been planning his wedding to devoted fiancé Carly Blackman, 33, with the help of their daughters Macie, six, Maddison, five, and his step-daughter Bayleigh, 13.
At the time, Carly’s mum Rebecca Watson, said his death was a “mystery” and the family man was “happier than ever” and had “everything to live for”.