Possible Clues:

• Short opera in festive performance thus mounted in islands
• Island group giant tortoises
• Thus break a prisoner returning in these islands
• Darwin stopping point, with 'the'
• Unique group celebrations securing leading place in the past
• Group of islands off South America known for unusual animal life
• Islands, quiet in the past, engaged in festivities
• Ecuadorian archipelago suffering an infestation of rats?
• Pacific islands in this way break a criminal up