Kerala runs 580 kilometres down the Malabar coast, and changes completely every fifty of them. There are the backwaters — a lattice of lakes and canals best seen from a slow houseboat — then the Cardamom Hills, where tea covers the slopes in clipped geometry, and finally Fort Kochi, a port town layered with Portuguese, Dutch and Jewish history. Ayurveda here is not a spa treatment; it is a functioning medical tradition.