In a large bowl combine 3 cups cubed watermelon; 2 large ripe tomatoes, chopped; 1 medium cucumber, peeled, seeded and chopped; 1 small red onion, sliced; ⅓ cup pitted kalamata olives; ⅓ cup crumbled feta; and some chopped parsley and mint. Drizzle with olive oil and red-wine vinegar, sprinkle with salt and pepper, toss and serve.