In the serving glass, stir together the rum and maple syrup (or honey).
Pour in the hot water. Garnish with a lemon wedge, squeezing in the juice, and the cinnamon stick.
Variation for 8 servings: Warm 4 cups water, 1 ½ cups rum, and 4 tablespoons maple syrup on the stovetop until hot but not boiling. Garnish with lemon and serve.