Scene: our lake, a coüple of years ago. I was sailing alone, my Dulcibelle, just enjoying the peace and quiet, and the sailing! Enter Stage Left, Grandad with about 12 year old Grandson, Grandad carrying one of the large yellow Subs, made either by Graupner or Robbe, Expensive anyway. after asking what Channel I was on, Grandad prepared said Sub, Grandson, who was wearing Wellies, put the vessel in the water, then Grandad slowly drove it away from the shore into the deeper water. Dive! Dive! Dive!! called the lad, Grandad duly moved controls and the boat submerged, wonderful!! It remained visible for several seconds due to its yellow colour, then it went deeper, and disappeared, never to reappear! despite frantic stick waggling and searching, it never came back. Our lake is 50feet+ deep and seriously large, I wonder how far it went before the batteries went flat?