In the north of Zanzibar, you can find one of the natural lagoon full of sea turtles. In Baraka Aquarium they are buying the turtles, caught by fishermen and they are releasing them back to the fresh ocean water in the lagoon.
Use the unique opportunity to swim with sea turtles.
During the visit you can also feed turtles with sea weed or just spend your time in the water. Also, you can take snorkelling mask to dive and watch them in their natural environment.