For me it has always been water skiers or tubers. Every time they are around I have my head on a swivel since they sometimes turn without looking or pull someone across your patch. I remember when I was younger and we were at Torch Lake and a water skier got run over and killed. We saw the boats collecting the body. Ever since then I try to keep a very healthy distance from skiers and tubers and always try to scan the water in front of me for a dropped skier or tuber.