The woman, a guest at Go Ape! Tree Top Adventure Course at the park at 1068 Howell School Road, fell 40 feet about 1:40 p.m..
She was treated by New Castle County paramedics and taken by ambulance to Christiana Hospital in Stanton, where she was pronounced dead.
Her name is being withheld by police pending notification of next of kin.
Police said there were no other injuries and they are still investigating, with more information to be released later.