Carry the Flag. Scrawling HELP in the sand might, but if you’re heading into the wild, you’ll want something more reliable. The Coast Guard and all four branches of the military use the SEE RESCUE STREAMER ($68; www.SeeRescueStreamer.com), a cigar-sized pouch that contains a 25-foot-long orange nylon penant. It’s 50 times as easy to spot as your T-shirt, and unlike a flare, it won’t burn out.