Maui fire officials said a 43-year-old woman from Fremont, California suffered a life-threatening injury at the zip line at the Maui Tropical Plantation Monday.
Crews were dispatched to the scene just before 10:30 a.m.
The woman was on the middle tower, about 40-feet-tall, and was accessible only by air or zip line.
Two fire personnel and a medic went on the zip line to assess the patient's condition. She was diagnosed with a femur fracture on her left leg.
She was airlifted off the tower and taken to an ambulance waiting in front of the plantation. The woman was taken by ambulance to Maui Memorial Medical Center.
Fire officials say the woman hurt herself as she was coming down the zip line and landing on the tower.