The holidaymaker got into trouble in the water around lunchtime yesterday at Prussia Cove, Cornwall, between Helston and Penzance.
It comes as two other men were reported to have died in the sea at Babbacombe Beach near Torquay, Devon yesterday.
Police and the emergency services, including RNLI lifeboats, coastguard rescue teams and the air ambulance were all scrambled to Prussia Cove to rescue the swimmer.
But despite their best efforts, police confirmed today that the man could not be saved.
“Police were called to Prussia Cove near Penzance following reports that a man had got into difficulty in the sea”
Devon and Cornwall police
A spokesman for Devon and Cornwall Police said: “Police were called to Prussia Cove near Penzance around 1.05pm today [28 June] following reports that a man had got into difficulty in the sea.
“He was recovered from the water by a lifeguard and treated by ambulance.
“He was taken to Praa Sands and was sadly confirmed deceased a short time later.
“Falmouth Coastguard, RNLI lifeguards, police and ambulance all attended.”
Police have yet to release the victim’s identity as they work to trace his next of kin.
HM Coastguard said: “At around 12.50pm today (28 June) HM Coastguard received multiple calls reporting a person in difficulty in the water at Prussia Cove, Cornwall.
“Penlee RNLI Lifeboats, Penzance Coastguard Rescue Team and the Newquay Coastguard helicopter were all sent to the scene alongside Praa Sands Beach Lifeguards, South West Ambulance Service, a Helimed and Devon and Cornwall Police.
“The person has been recovered from the water.”