Who is the patron saint of sailors?

Saint Erasmus of Formia, also known as Saint Elmo, was a Christian saint and martyr, who died c. 303. He is venerated as the patron saint of Sailors and abdominal pain. St Erasmus or Elmo is also one of the Fourteen Holy Helpers, saintly figures of Christian tradition who were venerated especially as intercessors.

Saint Erasmus may have become the patron of sailors because he is said to have continued preaching even after a thunderbolt struck the ground beside him. This prompted sailors, who were in danger from sudden storms and lightning, to claim his prayers. The electrical discharges at the mastheads of ships were read as a sign of his protection and came to be called "Saint Elmo's Fire".

Pope St Gregory the Great recorded in the 6th century that the relics of Erasmus were preserved in the cathedral of Formia. When the old Formiae was razed by the Saracens in 842, the cult of Erasmus was moved to Gaeta. He is currently the patron of Gaeta, Santeramo in Colle and Formia.

There is an altar to St Erasmus in the north transept of St Peter's Basilica. A copy of Nicolas Poussin's Martyrdom of St Erasmus serves as the altarpiece.