The boat of Saint Peter (Italian: barca di san Pietro) is a popular rural tradition prevalent in northern Italy, particularly in the geographical area of Friuli-Venezia Giulia, Veneto, Trentino, Lombardy, Liguria and Piedmont.

[2][3] On 28 June, the Saints Peter and Paul's eve, people put an egg white in a bottle which they leave on the windowsill in the open air until the next morning; albumin, coagulated in filaments, resembles the masts and sails of a boat.

According to popular folklore, the effect is produced by Saint Peter, who, whilst blowing in the glass container would make the egg white take the shape of a boat.

[5] The phenomenon is due to the thermal variations between day and night, also compared to the ground on which the bottle is placed, typical of the first summer time, which lends itself well to these conditions (provided that the earth has warmed up the eve).

Likewise, the bottom, in contact with the heat of the ground on which it rests, should raise the water molecules upwards, by small convective movements, and create the effect of the veils of egg white.