Mix syrup with seltzer water for a refreshing drink, or drizzle over yogurt, pancakes, or ice cream.
With a sharp knife, slice off top and bottom of pineapple. Holding fruit upright on cutting board, slice off peel in strips; reserve peel. Cut flesh into 8 wedges. Remove core; reserve. Refrigerate wedges for another use.
Cut reserved peel and core into 1-inch pieces; place in a medium saucepan with ginger, sugar, and 4 cups water. Boil until reduced to 1 cup, 25 to 30 minutes. Strain, discarding solids; chill.
Mix syrup with seltzer water for a refreshing drink, or drizzle over yogurt or pancakes.