Dietitian's tip: Aguas frescas are popular fresh-fruit drinks in Mexico. Although water is a standard ingredient, this undiluted version is a thirst-quenching refresher whether accompanying spicy foods or sipped in the sun.
Place the melon in a blender or food processor. Process until smooth. Pass the puree through a fine-mesh sieve placed over a bowl to eliminate the pulp and clarify the juice. Pour the juice into a large pitcher. Add the cranberry and lime juices and stir to combine. Refrigerate until very cold. Pour into tall chilled glasses and garnish each with a fresh lime slice.