In the latest mishap, officers say 42-year-old Hope Densford was driving a jet ski with a tour group on Choctawhatchee Bay.
When the group's leader signal a stop, they say she missed the signal.
Ms. Densford then ran into another watercraft hitting her sister-in-law, 42-year-old Denise Spivey.
Spivey was hospitalized with serious back injuries.
This was the second serious accident on Destin area waters in less than a week.
Several days earlier, 43-year-old Scott Sheffield of Cartersville, Georgia suffered serious injuries when his 18-year-old son Scott ran into him on another jet ski.
This accident happened near the Jetties East Condominiums.
Ms. Densford and Scott Sheffield, Jr. both have been charged with reckless operation of a watercraft.