There's a difference between a myth and a legend.
Nevertheless, not everyone would agree with you
Because another story on Heracleion is titled:
'Thought To Be A Myth, An 8th Century B.C. Egyptian City, Heracleion, Was Found Sunken 150 Feet Underwater'
The article states that:
'Until a decade ago, no one knew if Heracleion, believed to be an ancient harbor city, was fiction or real. Now, reports the Telegraph, the researchers who found it 150 feet beneath the surface of Egypt's Bay of Aboukir are sharing some of the amazing historical artefacts preserved there. The finds include 64 ships, 16-foot-tall statues, 700 anchors and countless gold coins and smaller artefacts'.