1 to 2 juicy limes (you need 1-ounce juice and a wheel for garnish)
1 ounce golden rum, such as Gosling's
6 ounces ginger beer
1/2 ounce dark rum, such as Goslings's
Fill a highball glass or large wine goblet with ice cubes. Add the lime juice and the golden rum. Top off with the ginger beer and stir lightly. Float a layer of the dark rum on top by pouring it over the back of a wide, flat spoon. (Don't worry if it doesn't float; it tastes great either way.) Garnish with the lime wheel. Drink.