Methods, apparatus and systems for determining the location of a marking device during performance of a marking operation using triangulation are described. The marking device may be of the type used to mark the presence or absence of underground facilities and may include a marking material dispenser to dispense marking material as an indicator. The marking device may include a transmitter which transmits a signal received by a receiving system including two or more receiving devices at separate locations. Triangulation algorithms may then be used to determine the location of the marking device relative to the receiving system.