RedactedNarrative: It was the first time the Skier had been on a knee board.  Operator and Passenger provided instruction, including hand signals to use.  Towed skier west to end of lake and turned east back to origin/drop off point.  Drop-off area obstructed by local ski team members and equipment, Vessel 1 Operator turned west proceeding approximate half the distance back to the end of lake and again turned east to attempt drop-off of skier.  Drop-off area still obstructed, so another turn to the west was taken.  Skier entered turn outside of the wake and continued outside wake through turn.  Upon completion of turn, skier was headed toward downed tree in lake.  Skier let go of rope and continued to slide into the tree.  Skier sustained an open dislocation to the right talus, fracture, torn tendon to pinky toe and abrasion to forehead upon impacting a tree.