In a small saucepan, combine the sugar and water and cook over medium heat just until the sugar dissolves, stirring occasionally. (Alternatively this can be done in a microwave-safe bowl in the microwave). Remove from the heat and transfer to a medium bowl. Set in the refrigerator to cool completely. (Adding the zest and mint while the sugar mixture is still hot will cause discoloration). Once the sugar mixture is completely cool, add the lime zest, juice, mint, and salt. Stir until combined.

In a large bowl, combine the strawberries, cantaloupe, watermelon, and blueberries. Pour the lime-mint syrup over the fruit and gently toss until combined. Enjoy!