For the moment, the Parc Communautaire de Sakaviro Miray, a community conservation project preserving a small patch of forest that is home to three groups of semihabituated ring-tailed lemurs, is little known to international visitors. There are currently three different walking circuits, plus you can take a kayak out onto the river to look for crocodiles. Guides (some of whom speak English) are available.
To reach the reserve, drive 7km west of Ambalavao to the village of Laritsena and then head 5km NW on a bumpy track. It's vital to phone in advance and let them know you're coming, otherwise there won't be any guides waiting.