Rinse the watermelon under cool water, slice off the ends for stability, cut into quarters, remove rind, and cube into bite-sized pieces.

Rinse and pat dry the cucumber, slice it lengthwise, cut into half-moon shapes, and combine with the watermelon.

Rinse mint leaves, chop them, and sprinkle over the watermelon and cucumber mixture in the bowl.

Crumble feta cheese if using and sprinkle over the mixture evenly.

Combine olive oil, lime juice, salt, and pepper in a small bowl, whisk until blended.

Pour the dressing over the salad mixture and toss gently until evenly coated.

Serve immediately or chill in the refrigerator for up to an hour before serving.