... Visit Isalo national park.
This activity in itself is an off beat path activity.
Not only you would see the lunar landscape made up by those ruiniform rocks, on which wind and rain have combined their actions;
Not only, you would be pleased to see those endemic species, fauna as well as flora;
Not only you would appreciate the little bath in fresh rockpool water at the end of your trek;
Not only you would be able to visit the neighbouring Malagasy Far west (check my "Saphire road" tip),
you would experience too a rendez-vous with yourself, facing immensity, silence in the canyon when noone is around except you and your guide, echoes in the galleries and oasis....