APPROXIMATELY 4 1/2 MILES NORTHEAST OF THE ST LUCIE INLET, V1 WAS ON A SOUTHERLY HEADING GOING TOWARDS THE ST LUCIE INLET. V2 WAS DRIFTING IN THE WATER. V1 OBSERVED V2 FROM A DISTANCE. AS V1 APPROACHED, V2 POWERED UP AND TURNED AROUND TO PROTECT HIS DIVERS IN THE WATER. AT THIS POINT V1 OCCUPANTS NOTICED THE DIVER DOWN FLAG AND THE OPERATOR BEGAN EVASIVE ACTIONS. THEN V1 OPERATOR FELT THE IMPACT AS IF THEY HIT SOMETHING. V1 RAN OVER ONE SCUBA DIVER. THE DIVER SUFFERED SEVERE LACERATIONS TO BOTH LEGS BELOW THE KNEE, WHICH RESULTED IN BILATERAL AMPUTATION.