Blend the watermelon until completely smooth, then pour it into a large pitcher, add the fresh lime juice, honey, and 2 pinches of salt, and stir thoroughly until the honey is fully dissolved and the base is uniform, lightly opaque, and aromatic.
Pour in the ice-cold water and stir gently to combine without foaming, then add the watermelon slices and lime slices for visual clarity and a light secondary aromatic infusion.
Refrigerate for at least 1 hour for a clean, fresh flavor; for a more expressive watermelon character, infuse up to 4 hours, but do not exceed this time or the blended watermelon will lose brightness and start tasting dull.
Serve well chilled straight from the pitcher, or over ice if preferred, keeping the fruit in the water for aroma and presentation.