Baptism by triple immersion
Byzantine rite · Eastern Orthodox Church · Greek
Three immersions in the one Name, and the East treats the form as the thing that makes a baptism recognisable when somebody comes over.
three immersions, one for each Person
A form of Baptism — The rite of entry. The councils legislate its form less than its recognition: whose baptism counts when somebody comes over is the question the third and fourth centuries actually fought about.
After The Rudder (Pedalion) · the Rudder, on the Apostolic Canons, canon 50.