Uruguayan Spheres

While camping at the beach (not near a city, at night, very clear and calm) with my dad, his friend, my sister and other friends we observed a sphere of intense, blueish light appearing on the water (calm ocean that night) at about 100 meters from shore.  It was perhaps 10 meters in diameter (30 feet).  No sound emitted.  
We could see it clearly and close at about 500 meters away from us.  My dad looked at it with binoculars but could not discern a mass on it, the light hurt his eyes like the sun does.  
After a few minutes about 5 or 6 other smaller spheres came out of it.  They lit up the water! 
In time they lined up parallel to shore and began moving in our direction over the water, not touching it.  They stopped on shore right in front of us, very close at a distance of about 160 meters or less.  They just stood there, shining, we got very scared.  
My dad and his friend (both psychologists who worked for the Uruguayan government) thought it prudent to leave the beach in a hurry back on our way home.  We did!.  
My dad and his friend could never find an explanation for what we saw that night.  It was a very traumatic experience!
Witness elects to remain totally anonymous; provides no contact information.  PD