Prison Island trip From Forodhani garden by boat you will be picked up to explore the shores of Prison Island. Despite the island's dark history, it has become a sanctuary for rare Aldabra giant tortoises. Watch in awe as these massive, shelled creatures amble about the island, munching on sweet grasses and snoozing in the sun. With the eldest tortoise at a ripe old age of 200 years old, it's amazing to see them up close. A sliver of green in the Indian Ocean, the island also makes a fantastic launching pad for a spot of snorkeling or swimming in the turquoise shallows, sun bathing on the silver sandy beach is additional activity..