Cube the watermelon and add it to the blender.
Add the tequila, sea salt, lime juice, and ice to the blender.
Blend until smooth, ensuring the mixture is well combined.
Taste the mixture and adjust sweetness by adding agave syrup if needed.
Pour the cocktail into chilled highball glasses for the best presentation and serving experience.
Garnish with a slice of watermelon or a lime wedge for a decorative touch.
Serve immediately and enjoy the refreshing flavors.
Stir gently before drinking if the mixture separates.
For a frothy texture, you can use a bit of whipped cream or egg whites for a luxurious finish (optional).