A device of the nature of a sea-anchor has a body tapered to the nose where it is attachable to a cable from a boat and formed with ports normally closed by spring-loaded closures but opened, by predetermined cable tension, to increase resistance to passage through water. Tail fins behind the body, and water passages through the body restrict rotation of the device. A chamber in the body when air-filled converts the device to a distress buoy, the tail fins uppermost to serve as a radar reflector, aerial for a distress transmitter in the body and carrier for a light.