Combine cherries, strawberries, and raspberries in a large bowl.

Pit the cherries if desired.

Use a melon baller to cut balls from the watermelon, or cut into cubes.

Add watermelon to the bowl with other fruits.

Combine chopped mint and caster sugar in a small bowl.

Crush the mint and sugar together using a rolling pin or mortar and pestle until well combined.

Sprinkle half of the mint sugar mixture over the fruit.

Squeeze the juice from one lime over the fruit.

Mix gently to combine all ingredients.

Let the mixture stand for 10 minutes until a syrup develops.

Serve in a large bowl with the remaining mint sugar and lime wedges on the side.