There are typically three primary classifications for UFOs. The first, and the most familiar, is UFO or unidentified flying object. The second, and not so familiar, is USO or unidentified submersible object. These objects are witnessed traveling in and through water. The third classification is known as a trans medium craft. These objects have the ability to move into, through, and out of, outer space, the Earth’s atmosphere, and water. So when it comes to USO’s, it is not surprising that submarines have had unexpected contact and you can learn more in this article written by Brent Swancer writing for MysteriousUniverse.com, HERE.