I spent 3 weeks on the Tortoise Breeding Centre programme ran by IOI a few weeks ago. The experience was amazing. It was so much fun working with the Giant Tortoises everyday, you really got to know some of them and learn their characters. The working day was 8am - 12 which meant we had the entire afternoon to snorkel, relax on the beach, surf or just stroll around. I have to mention the accomodation is beautiful too :)
All in all I would throughly recommend this programme. I booked through Working Aborad and they were also amazing. I will definitely be back.