The dramatic mountain range that divides the island of Santo Antao into two, with peaks rearing up to 4,921ft (1,500m), make it attractive for trekking, particularly through the tropical vegetation of the deep green valleys which encase the 16th-century town of Povoacao. Visitors can reach Santo Antao by ferry from the port of Mindelo on the more populated island of Sao Vicente, arriving at Santo Antao's small port of Porto Novo. In contrast to the mountainous interior, the island's coast is rugged and bare, but sugar cane, bananas and coffee are grown by the locals. Sugar cane is the raw material for the famed Cape Verde rum, called 'grogue', which is produced here and enjoyed by visitors and locals alike. A walk around the main town of Ponta do Sol is recommended to enjoy the vista of some old colonial buildings, and the main site of historic interest is a mysterious inscribed rock near Janela dating from the 1400s, when the islands were believed to be uninhabited and undiscovered.