Abstract: A location marker includes a casing, a switch assembly and a lens enclosing a flashable strobe lamp. The location marker is powered by batteries and an electronic circuit that converts the battery voltage to a trigger voltage for illumination of the strobe lamp. The switch assembly is non-intrusive and maintains water tight integrity inside the casing. The switch assembly futher includes a magnetically operable switch for selectively connecting and disconnecting two pairs of terminals. An R.F. transmitting location marker is also employed using a transmitter circuit and an antenna.