A 77-year-old French woman drowned as she swam in the sea off Les Deveses beach in Denia, according to the Information and Emergency Coordination Centre (CICU).
The woman was pulled unconscious from the water at 11.20am near Calle Rio Serpis as yellow flags waved.
Lifeguards began CPR which was continued by a team of SAMU medics.
As the woman did not respond to CPR, medics ordered a defibrillator from the health centre at Les Deveses.
After 10 minutes, the woman was breathing however just seven minutes later she suffered a second cardiac arrest.
Medics tried for 45 minutes to resuscitate her again without success.