U.S. Navy destroyer escort dispatched to Puerto Rico to observe unknown underwater contact which remained undetermined.While I was serving in the U.S. Navy during the summer of 1980 or 1981, my ship, the USS W.S. Sims, FF 1059, was urgently dispatched to Puerto Rico. We were initially told that a Russian submarine was detected which was making suspicious manuevers in the vicinity of Puerto Rico. We spent several weeks with divers, scientists and other experts on board, attempting to determine what was going on. I was informed that the divers had remarked that this incident was another "Shag Harbor". I only learned many years later after leaving the U.S. Navy, through watching programs on cable like "Sightings" and other programs on The Learning Channel and Discovery Channel about Shag Harbor in Nova Scotia and also that UFOs were reported to be operating in the waters off Puerto Rico. We never were told anymore about the result of this mission other than that it had been determined that a natural phenomenon of undetermined origin had been studied, that was capable of mysteriously eluding detection at will only to reappear again. This went on for about 6 weeks if I remember correctly.((NUFORC Note: Date is approximate. We have encouraged the witness to have other members of the cress of the USS W.S. Sims submit reports of their recollections, as well. PD))