RedactedNarrative: Vessel travelling downstream on Wisconsin River ran aground on a sand bar at approximately 6:45 pm.  Operator voluntarily left vessel to push vessel off of sand bar.  Passenger takes control of vessel, which has throttle still engaged.  Passenger stated that due to her inexperience operating vessels, she immediately ran aground on the sand bar again.  Operator/Victim attempts to push vessel off of sand bar a second time, but steps into a deep hole and struggles to stay above water.  Passenger throws a Type IV throwable personal flotation device to Operator/ Victim, which he is unable to grab.  Operator/Victim goes under water and does not come back up.  Passenger attempts to maneuver vessel to Victim, but cannot get close.  Nearby fisherman arrives by vessel and instructs Passenger to call 911 while he attempts to locate the victim.  Three more people arrive in two boats and attempt to locate the victim.  WDNR, County Sheriff, and Fire Department conduct search in the area.  Marathon County Dive Team recovered deceased victim at 11:55 pm.  Deputy Medical Examiner pronounced Victim dead from an apparent drowning, autopsy was performed on 8/31/2016.  WDNR has not received the autopsy report as of 10/18/2016.