UPDATE 6.30pm: Inspector Rob Cutis said: "We believe the man is in his 50s.
"He was in a critical condition when he was airlifted to hospital but we cannot give any more details of his condition at this moment.
"The male was found on his own. We do not know if he is down here alone or with family."
EARLIER: Beach-goers attempted to resuscitate a casualty plucked from the sea at Prussia Cove, near Penzance.
A Falmouth Coastguard spokesperson said a rescue helicopter from RNAS Culdrose was sent to the scene as well as a coastguard team from Penzance and Devon and Cornwall Police, shortly after 4pm.
He added that members of the public nearby had attempted to give the man CPR.
The man was airlifted to the Royal Cornwall Hospital at Treliske, Truro.