De Koffiemolen is the working windmill on the western edge of Formerum and the village's centrepiece. It is a smock mill built in 1876, restored to working order, and ground grain into the 1960s. The miller still raises the sails on most days and the mill is open as a small museum and café — the collection inside includes more than fifty antique coffee mills along with the original milling gear.
The café on the ground floor is famous for its cranberry tart, made with berries grown wild across Terschelling since they were accidentally introduced by a shipwreck in 1845. Stop for a coffee on the terrace, then climb the wooden stairs to see the millstones in motion.