River Antoine Estate is one of Grenada's great rum stops, not because it is slick but because it is gloriously old-fashioned. The distillery dates from the late eighteenth century and still uses a waterwheel to crush cane, with production methods that feel closer to agricultural craft than industrial spirits.
Tours usually walk you through the mill, boiling house, fermentation vats, and stills before a tasting of Rivers rum, which is famously strong. It is a short drive north of Grenville and combines well with Lake Antoine. Drink cautiously if you are driving; this is not polite little tasting-room rum.