I think it all depends on how crazy you are! Here 4 inches of black ice is good to walk on, anything less and you are looking for trouble. I was fishing on 4 inches and was walking along and goty to see the ice cracking under my feet! Needless to say I very slowly backed up. You see 4 inches is plenty strong enough but, how about 10 feet away when unknowingly the ice might be 2 inches thick? That happens here alot with the cold water springs we have coming up from the lake bottoms. So for the most part becarefull on the ice!