USO, when not referring to the United Service Organizations, refers to phenomena that can be seen underwater, entering the water or leaving the water that cannot be identified. In other words, USOs are unidentified submerged objects. Any object that is seen in the water by means of viewing, photographs, radar, sonar, and/or by hearing or audio recording that cannot be identified qualifies as an unidentified submerged object, or USO.
USOs and their counterparts UFOs (unidentified flying objects) are often associated with the supernatural. However, these objects are characterized by being unidentified or unidentifiable. The first person in the world to see a whale was viewing an unidentified submerged object and the first person in the world to see a bird was seeing an unidentified flying object. Therefore, you see, not all of the sightings of USOs and UFOs that you hear about are going to be alien-related, if any. All stories of what these objects may be is speculation until proven.
In some cases, USOs or unidentified submerged objects are also UFOs, or unidentified flying objects. One famous example of these is the “foo fighters” of World War II. No, we are not talking about the rock band. In fact, the rock band was likely named for these phenomena. During World War II, a number of military pilots, soldiers and navy crewmembers reported seeing strange lights and aircraft in the skies. These were reported by military personnel on both sides of the war. In some cases, these crafts or lights seemed to chase or antagonize military aircrafts. They were even seen entering and leaving the ocean. In these cases, the foo fighters were both USOs and UFOs.
Other examples of unidentified submerged objects are lights seen beneath the surface of the water. There are numerous examples of strange lights being seen all over the world. Stories about strange lights range from hovering UFOs to the Brown Mountain Lights of North Carolina, which are UFOs in their own right. There is no reason why the ocean would be the exception. These lights could be a number of different things, but no verifiable theories have become known.
There are countless examples of unidentified submerged objects being spotted. Military personnel, oceanographers, marine biologists and average Joes have reported blips, bloops, strange shapes on radar, lights glowing beneath the surface, objects shooting up out of the water and much more in our oceans. These sightings are so varied that they probably have different causes. In fact, some sightings of USOs like strange noises have been explained since they were reported and we can say with certainty that the causes of those USOs are not the same as others. Therefore, it is impossible to say that all, or any, USOs, or UFOs for that matter, are of supernatural or alien origin.
Smith, S.E., What is an Unidentified Submerged Object?, retrieved 8/1/10, wisegeek.com/what-is-an-unidentified-submerged-object.htm