I experienced this while making my own mission in the editor. Placing naval mines and having stormy weather I noticed the naval mines do not float with the surface of the waves. For example when a large waves passes the mine will disappear underwater and when the waves has gone they appear in mid-air above the water looking like they are supported by a ridged pole. In other words they do not move with the surface of the water. Nothing major but look a bit silly when they are stuck up in the air. See image.

Also my assault craft failed to set off the mines but this issue has already been raised by someone else. {F17657}