Sidney Good and Alexis Fairchild, both 17, were parasailing Monday in Panama City Beach when strong winds snapped the rope connecting their sail to the boat below, the New York Daily News reported.
"Both girls sustained head trauma as well as multiple severe lacerations. Alexis has severe back injuries and Sidney has neck trauma. However, we are fortunately seeing some positive signs from both Sidney and Alexis," their parents said in a joint statement Thursday.
Both girls have undergone surgery to repair extensive injuries.
"Thank you again to all who are thinking of and praying for our girls. Your prayers are working!" the girls' parents said.
The Florida Fish and Wildlife Conservation Commission is investigating the incident.
Florida lawyer Waylon Thompson said this is not the first time parasailing company Aquatic Adventures has been involved in such an accident.
In 2009, two teenagers, also from Indiana, were tossed into the ocean after their parasailing rope snapped, Thompson said, suggesting that employees at the company are more concerned about making a commission than customers' safety on days when the weather is bad.