Abstract: A distress marker assembly in the form of an inflatable balloon fastened to a cylinder of compressed helium or hydrogen gas, with a flexible line fixed at one end to the cylinder and at the other end to an anchor unit. The anchor unit is shaped with a clasp for fastening to a fixed object or the person of the user, and formed with a pair of flexible clamp jaws through which the line is fed out to the balloon, when inflated. The balloon is marked with a distinctive color and with large letters spelling out S.O.S. The balloon contains a quantity of metal oxide powder to serve as a radar reflector.