We visited the Sea Turtle Rescue on SPI. The $6 entrance fee is very reasonable for what you are about to see and learn. The Rescue rehabilitates sick and injured turtles and then releases them back into the ocean if possible. Alot of these turtles get sick by eating plastic floating in the garbage or get entangled and injured by plastic or fishing line / hooks.
I believe they also host release events that we need to keep an eye on for.