In a small bowl, whisk together the lime juice, lime zest, and honey until the honey is fully dissolved and incorporated. The acid from the lime juice helps break down the honey and creates a smooth dressing. Stir in the finely chiffonade mint and a pinch of sea salt, which will brighten the flavor and balance the sweetness. Set the dressing aside while you prepare the fruit.
In a large bowl, combine the watermelon cubes, hulled and quartered strawberries, blueberries, blackberries, and raspberries. I like to add the more delicate berries (raspberries and blackberries) last and handle them gently to avoid bruising them. Make sure the watermelon is cut into uniform 1-inch cubes so each bite has a consistent texture and the fruit combines evenly.
Pour the lime-honey dressing from Step 1 over the fruit from Step 2 and gently toss to combine, being careful not to crush the berries. The dressing will coat the fruit and the flavors will start to meld together. Let the salad sit for 5-10 minutes at room temperature to allow the flavors to develop, or refrigerate until ready to serve. I prefer to dress the salad just before serving so the fruit stays fresh and doesn't become too watery.
Transfer the salad to a serving bowl or individual glasses. Garnish generously with fresh mint leaves and thin lime slices for a bright, fresh presentation. Serve immediately to enjoy the fruit at its best texture and the vibrant flavors at their peak.