In a large pot add the water, sugar and cinnamon stick. Bring to a boil, stirring to dissolve sugar and then remove from heat.
Add hibiscus flowers, gently pushing down to submerge the flowers with a spoon. Steep the tea for 30 minutes, but no longer than 2 hours (it will get bitter).
Strain hibiscus flowers and cinnamon stick from tea into in a pitcher to cool. Refrigerate your Agua de Jamaica and serve over ice with a squeeze of lime.