A mesmerizing and intricate Halloween-themed illustration featuring Jack Skellington and Sally, now transformed into mermaids, in a spooky ocean city at night. Jack, sporting a ghostly skeleton appearance, is seen beside Sally, who has become a mysterious sea creature. They swim gracefully through the haunted underwater city, surrounded by bioluminescent fish glowing in vibrant hues and eerie-looking coral formations. The cityscape in the distance is adorned with skulls and pumpkins, creating a psychedelic and otherworldly atmosphere. The scene is illuminated by a mysterious, luminescent green light, further enhancing the enchanting and eerie ambiance., illustration, whiet background