Equatorial Baptism
Baptism on the line, also called equatorial baptism, is an initiation ritual sometimes performed as a ship crosses the equator, involving water baptism of passengers or crew who have never crossed the equator before. The ceremony is sometimes explained as being an initiation into the court of King Neptune.
The ritual is the subject of a painting by Matthew Benedict named The Mariner"s Baptism, and of a 1961 book by Henning Henningsen named Crossing the Equator: Sailor"s Baptism and other Initiation Rites.