In a large bowl, combine the cubed watermelon, diced cucumber, sliced red onion, cubed feta cheese, and kalamata olives.
In a small bowl, whisk together the lychee white balsamic vinegar with basil olive oil until well combined. Season the vinaigrette with salt and pepper to taste.
Drizzle the vinaigrette over the watermelon salad and toss gently to coat all the ingredients.