Using a chef's knife and cutting board, chop the watermelon into approximately 1-inch cubes and place them into a large serving bowl.
Slice the peaches into thin, even wedges, then add them to the bowl with the watermelon, ensuring even distribution of both fruits.
Tear fresh basil leaves into small pieces with clean hands, releasing their aromatic oils, and sprinkle over the fruit mixture.
Sprinkle flaky sea salt sparingly over the salad, visually contrasting with the bright colors of the fruit.
Gently toss all ingredients together using two large spoons until well combined, ensuring the basil and salt distribute evenly.
Serve the salad immediately in individual bowls or a large platter, showcasing the colorful mixture of fruits and herbs.