Zirganos was born in 1910 in Volos, Thessaly, one of ten children in a large family. He saw action in World War II against the Italians and was decorated for valour. In 1949, he swam the English Channel for the first time. On August 22, 1950, once again he successfully swam the English Channel, beating his 1949 time by more than two hours (16hrs 19mins). On 16 August 1951 he did even better, completing the same crossing in 14hrs 1min.
Zirganos also successfully swam the Bosphorus, the Nile and twice swam around Manhattan island, New York.
He died in 1959, after he unsuccessfully attempted to swim the notorious 23-mile North Channel between Northern Ireland and Scotland (the Irish Sea). Within three miles of the coast he lost consciousness and died despite the efforts of a doctor who cut him open with a borrowed penknife to massage his heart.