saucer like disc submerging from waters, disapears instantaneously, water boils before submerging.

I live on a reservation called Lac Du Flambeau.  We have multiple stories of saucer like discs submerging from our lakes and disappearing instantaneously, as one story that was reported more then once.  
Their were four men fishing on Flambeau lake.  When  a complete circle of water started boiling, after 20 seconds or so these men saw a saucer like disc submerge from the water and cause great waves in the area.  
They said the saucer levitated off the ground for about 6-10 seconds.  After that they saw it travel speeds beyond any aircraft or any sort of object they’ve seen, in a blink of an eye it vanished.  
Even many years ago our people been seeing mysterious objects in our sky and we even have a Indian word for an UFO. 
Nobody has been able to explain this and there are multiple witnesses.
No specific dates indicated for multiple sightings.  PD