The curl created by the current along the outer edge can break off under your weigt dumping you into deep moving water unexpectedly. I have many case history's of this happening. Also on the Mississippi River true stories of people walking on huge sandbars having the bar between them and shore sink away and fill with water. One fellow told me in his area they have people disappear on them never to be found again. Sounds like a quick sand or sink hole situation, neither one is good.
https://www.youtube.com/watch?v=jeoGEPy3WOE