We believe it may be a sea serpent hungry for breakfast, lunch, snack, or dinner.  Also, it could be a mega-mouth, a huge shark with an oversized mouth. One mega-mouth has been found with an anchor inside its stomach.  Maybe it is some kind of warning from an unknown galaxy.   It might be some test used by aliens to see if humans can live longer on Mars with the thin layer of atmosphere that scientists found.  Maybe underwater caves suck in water and create a tidal wave, or suck in the vessel itself.  Maybe tsunamis, waves, that are formed by underwater earthquakes, destroy the ships and even low flying planes!  Tsunamis can travel 500 miles per hour and be 50 feet high!  Or the cause  may be solar flares. Solar flares disrupt compasses and radio waves.