Abstract: A probe generally rocket-like in shape includes a forward leading nose section containing a radio transmitter with an antenna permanently attached thereto which is fixed to a central housing section possessing a generally cross-sectionally square bore followed by a trailing finned section continuing the bore. A motor assembly including an electric motor having opposed shafting (one end of the shaft defines a cutting tool and the opposite end of the shaft defines a plurality of threads) is slideably disposed in a watertight chamber. The motor assembly, retained in a first position by the engagement of the threaded shaft with the body, is biased toward a second position by a compression spring. A sensing array of position sensing switches senses deviations in the descent of the probe in the water. The motor rotates the shaft to disengage the shaft from body in response to the sensed deviations.