The giant tortoises, a prominent attraction on Prison Island, are scientifically known as Aldabrachelys gigantea. Belonging to the family Testudinidae, the Aldabra giant tortoise is a species endemic to the Seychelles islands. Their presence makes them a main reason for visitors on Prison Island.

Giant tortoises exhibit robust, heavily scaled legs that provide essential support for their substantial body weight. The Aldabra giant tortoise is characterized by the long neck, this elongated neck enables the tortoise to reach and consume tree branches up to a meter above the ground. In general, females tend to be smaller in size compared to their male counterparts.

These tortoises, initially introduced to Changuu Island in Zanzibar as a gift from the British governor of Seychelles in 1919, were originally four Aldabra giant tortoises from the Aldabra island. Over the years, these remarkable creatures have not only adapted but thrived, multiplying in number. Their population has transformed them into a key attraction on Prison Island.