similar commercial thermoplastic polymer as now commonly used for most thread spools foamed polyurethane or poly ester urethane materials can be molded as spools wooden spools may also be used as well as any material of sufficiently low density to float the spool up toward the surface of the water in principle any strong thread or cord could be used as the payout line which remains tied at its free end 6 to the safety pin 8 which in turn is attached to the garment of the drowning person however very high strength monofilament nylon threads are readily available and are especially suitable for purposes of the present invention the line 6 is not intended as a means of pulling up the drowning person but rather as a locating means which can be followed down to the person underwater from the floating spool the cap 2 preferably has a small notch or slot opening 9 at its bottom edge 3 so that the thread end 6 runs freely from inside the cap for connection to the spring eye 13 at one end of the safety pin 8 the closure member 10 is preferably a sodium bicarbonate tablet such as an alka seltzer u00ae tablet which can be made or purchased at very.