While it wasn’t possible for Cerulean or Viridian to move out to sea to observe if it was big enough to be seen from a distance, they both knew from training just how far a fire could be visible or smelled, and they also knew that from three sides, there was little but open water as far as they could see, optimizing viewing distance. If there had been anyone curious, they would surely have been drawn to the fire, much as the moths were.