Operator was traveling up the Black River near the middle of the channel on the PWC. Occupant1 was sitting directly behind him, Occupant2 was directly behind her. While underway Occupant1 yelled out to Operator to watch out that there were people in the water. Operator looked down and saw two swimmers in the water right in front of him. Operator turned the PWC hard to port in an effort to avoid hitting the swimmers The PWC struck one of the swimmers, a male. Operator turned around and took Swimmer back to the sandbar area. Swimmer had some lacerations on his right back side. Swimmer went to Georgetown Hospital where he received stitches for the lacerations.