A human who was cursed 500 years ago to be a ghost, the curse can only be broken if an innocent and clueless person completes challange cove in the underworld and he plans to find that person, so he found Guest. Back at the helm after his Underworld betrayal, the Dutchman is terrifying yet deeply desperate. He remains trapped by his old fate. He rules with an iron fist, constantly searching the horizon for someone to break his eternal curse. He remains extremely manipulative, using what people want the most to lure them to the Underworld on his ship. He then plays the part of being their friend until he becomes human.

After her opportunistic plot to overthrow the Dutchman backfired, Barb's bitter and ruthless streak is dialed to the max. Stripped of her quartermaster rank, she is more manipulative than ever, furiously plotting her next betrayal to seize ultimate control of the deep sea. And yet she misses the friendship she shared with him, but can’t forget how he left her the first minute he got to go back to the surface. So if the Flying Dutchman ever finds another to break the curse she’ll try to warn them. If she can.

Having conquered the treacherous Underworld, SpongeBob's bubbly optimism is now paired with an unshakeable bravery. He remains a loyal fry cook, but he carries the quiet confidence of a hero who faced his deepest fears and won, proving his ultimate innocence and courage. He is a sea sponge and is still childish with his friend Patrick and has autism.

Patrick remains delightfully clueless, but he boasts massive pride over the Underworld journey. He highly exaggerates their terrifying seafaring adventure to anyone who will listen, blending his usual lovable goofiness with the proud swagger of a self-proclaimed elite pirate helper and is a starfish.

He remains deeply cynical, annoyed by the frantic rescue mission he was dragged into. He is secretly glad SpongeBob is back, but he publicly scoffs at the heroism. He focuses entirely on his art, desperate for quiet away from Mr. Krabs, Patrick, and SpongeBob. But will let Guest near due to them having some sort of artistic passion. He is a squid with depression.

He is incredibly proud of SpongeBob, mainly because his star fry cook was saved. His obsession with money is stronger than ever; he immediately capitalizes on the journey, selling Underworld-themed Krabby Patties and prioritizing high profits over actual heroism. He is a crab.

With her friends back from the terrifying Underworld rescue, Sandy’s scientific brilliance and karate skills are sharper than ever. She is proud of her friends conquering the Underworld, she immediately studied the Underworld minerals in her dome to analyze Underworld physics while remaining fiercely protective of her neighbors. She is a squirrel.