I personally have drilled on Green Mtn ice,only to find myself 30 feet above the water. The lakes water level can drop and leave a ice dome kind of cover. Please take the time to drill a test hole close to shore,to see whats under you. I found out there was no water under me about 50 yards from shore.The walk back to shore was not fun! BTW: I remember some years back,they had a small heard of Elk break through and die. Just be careful and drill a few test hole . . . .a good indication its safe is when there are groups of fishermen all ready fishing where you want to fish. They won't stay out if it not safe.