The descent into the ocean was surprisingly tranquil. As the Thousand Sunny sank beneath the waves of the Sabaody Archipelago, the sounds of the bustling surface world vanished, replaced by the deep, rhythmic hum of the sea and the gentle churning of the ship's ballast systems.
Through the iridescent, soap-like film of the Yar Yarman coating, the Straw Hat Pirates had a crystal-clear, panoramic view of the underwater world. The massive, thick roots of the Yarximan Mangroves stretched down for thousands of meters, acting like colossal pillars holding up the sea. Schools of brightly colored fish, massive sea turtles, and glowing jellyfish swam casually past the adam-wood hull.
"Woaaaah!" Luffy pressed his face flat against the resin bubble, his eyes sparkling. "It's like flying, but wet! Look at that huge fish! Sanji, can we eat it?!"
"We are not breaking the coating to catch a fish, Captain," Sanji exhaled a puff of smoke, casually wiping down a patio table. "Besides, deep-sea fish have completely different fat compositions. I'd need to adjust my marinades."
"I could just age it until it's tender," Bonney offered, lounging in a deck chair with a slice of pizza. "But honestly, I just want to get to Fishman Island. I hear their sweets are top tier."
"It is breathtaking," Vivi smiled, standing beside Nami at the railing. Caroo gave an affirmative, awe-struck "Quack!" as a school of silver fish darted past his beak.
"It truly is," Robin agreed, looking up at the shimmering surface light filtering down through the water. She reached out and gently poked the resin bubble with her finger. The surface yielded slightly, feeling like thick gelatin before pushing her finger back. "Fascinating. This bubble seems to share the exact same characteristics as the ones produced by the roots on the surface."
"It does," Nami nodded, checking her Log Pose, which was pointing straight down. "Rayleigh explained it before we launched. The resin is permeable to high-velocity force. That means if we need to, we can stick our weapons through the bubble, or Franky can fire the ship's cannons, and the projectiles will pass right through without popping the ship's coating."
"SUUUUPER convenient for naval combat!" Franky struck a pose near the main mast. "The Gaon Cannon is ready to fire whenever we need it!"
Usopp, who had been nervously gripping the railing, turned around. "Wait, so things can pass through it? What happens if something breaks it? Like, what actually pops this thing?"
"Well," Nami tapped her chin. "A single hole will just seal itself back up. But if it takes massive, widespread damage—like if we smash into a jagged reef, or if a Sea King takes a giant bite out of the hull and pokes multiple holes at once—the entire bubble will pop instantly."
"And if that happens at this depth," Robin added with a serene, pleasant smile, "the sudden, localized shift in oceanic pressure will instantly crush the ship into splinters, and our internal organs will violently implode before we even have the chance to drown."
The deck went completely silent.
"ROBIN! PLEASE DON'T SAY THINGS LIKE THAT!" Usopp shrieked, his eyes popping out of his skull as he grabbed Chopper, who was already crying anime tears.
"We're going to implode?!" Chopper wailed, clutching his fuzzy head. "I don't want to implode!"
"Gebababa!" Dory laughed, sitting cross-legged on the grass. "A warrior's death in the crushing dark! Not a bad way to go!"
"Speak for yourself," Kashii grumbled, adjusting his helmet. "I prefer dying with my boots on solid ground."
"Oimo agrees," the other giant nodded solemnly. "No imploding today, please."
"Don't worry, you guys," Merry chimed from the upper balcony, tapping her wrist console. "Sunny and I have the navigation locked in. We are currently passing through the Euphotic Zone and are about to exit the Disphotic Zone. We just hit one thousand meters below sea level."
"The light is fading," Sunny announced over the ship's speakers. "Activating the external luminescent floodlights."
Click. Massive beams of warm, white light shot out from the Thousand Sunny's bow and sides, piercing the growing darkness of the deep ocean. The water outside the bubble shifted from a vibrant blue to a deep, inky navy.
The crew settled in, enjoying the quiet ambiance of the deep sea descent.
Zoro was asleep against the mast, his arms crossed. Ben was sitting at a patio table, quietly reading a thick, leather-bound book on advanced genetic sequencing.
Suddenly, Usopp stopped shivering. He stood up straight, his hand reaching up to touch the rim of his sniper goggles. His brow furrowed in concentration. Over the last two years, his Observation Haki had sharpened into a highly sensitive, long-range radar.
"Hey," Usopp called out, his voice dropping its cowardly pitch. "I'm picking up a presence. A large one."
Zoro cracked his lone eye open.
"Is it a Sea King?" Brook asked, drawing his cane sword slightly. "Because my bones are not built for water pressure. Yohoho."
"No," Usopp pointed directly behind the Thousand Sunny, into the murky darkness above them. "It's a ship. And it's moving fast. It's heading directly toward us."
Ben closed his book. "Merry. Rear cameras."
"On it," Merry tapped her console. A holographic screen popped up over the patio table.
The screen displayed a dark, jagged pirate ship encased in its own coating bubble. But the ship didn't have paddle wheels or sails. It was being violently towed through the water by a massive, angry-looking sea monster with the body of a cow and the tail of a fish.
"A Sea Cow?" Sanji raised an eyebrow. "That's rare."
"They're gaining on us," Vivi noted, stepping closer to the screen. "Whose flag is that?"
The flag depicted a skull with slicked-back hair and a crossbones made of a scythe and a shovel.
"The Caribou Pirates," Robin identified easily. "Led by 'Wet-Haired' Caribou and 'Blood-Splatter' Coribou. Rookie pirates who recently made a name for themselves by hunting down and killing Marines. They have a reputation for extreme cruelty."
"Rookies hunting in the deep sea," Zoro grunted, standing up. "Must be targeting crews before they reach Fishman Island."
Outside, the Caribou Pirates' ship rapidly closed the distance, pulling up alongside the Thousand Sunny.
Through the water, the Straw Hats could see the deck of the enemy ship swarming with armed men. Standing at the bow was Wet-Haired Caribou himself, a tall, unsettling man with long, slicked-back hair, a long tongue, and a sinister, unhinged grin.
Caribou had been hunting weak crews, but when his lookouts had spotted the Straw Hat flag, his ambition had overridden his caution. He wanted the fame of taking down the 500-million-berry man.
Caribou raised a massive halberd, yelling commands to his crew. He pointed at the Thousand Sunny, his mouth moving as he ordered the assault.
"They're preparing to board," Franky cracked his metallic knuckles. "Shall I blast them with the laser beams?"
"Wait," Nami said, stepping up to the edge of the bubble and peering out at the monster towing the enemy ship. Her eyes narrowed. She recognized the green spots, the gold ring in its nose, and the dull, bovine eyes.
"Is that... Momoo?" Nami asked, absolutely baffled.
"Momoo?" Luffy blinked. He looked closer. "Hey! It is! That's the cow from Arlong Park!"
"The one we beat up?" Sanji asked, exhaling smoke.
On the enemy ship, Caribou leaped off his bow, sailing through the water toward the Thousand Sunny.
But as Caribou jumped, Momoo the Sea Cow happened to turn his massive head. The beast's dull eyes locked onto the Thousand Sunny.
Momoo saw Nami. He saw Sanji. And worst of all, he saw Monkey D. Luffy grinning and waving at him.
The traumatic memories of Arlong Park—the brutal kicks, the stretching punches, the sheer terror of being spun around like a toy—flooded the Sea Cow's brain in a tidal wave of pure, unadulterated PTSD.
Momoo's eyes bulged out of his head. He let out a muffled, underwater shriek of absolute, soul-crushing terror.
The Sea Cow didn't stop. He didn't hesitate. He violently whipped his massive tail, executing a flawless, high-speed U-turn.
With a surge of panicked adrenaline, Momoo bolted in the exact opposite direction, swimming away as fast as his fins could carry him, violently dragging the Caribou Pirates' ship with him into the darkness of the deep sea.
"WHA—HEY! WHERE ARE YOU GOING?!" Coribou's muffled voice faded into the distance as their ship was yanked away.
Plop.
Wet-Haired Caribou, who had already committed to his jump, passed effortlessly through the Sunny's resin bubble. His boots hit the grassy deck of the Straw Hat ship with a soft thud.
Caribou stood up, adjusting his coat. He kept his eyes closed, a sinister, arrogant smirk plastered across his face. He believed he had just led a glorious, terrifying boarding party.
"Kehihihihi!" Caribou laughed, his long tongue rolling out of his mouth. "Listen up, Straw Hats! You've had a good run, but your journey ends here! Men! Introduce yourselves to these fools! Slaughter them all, and bring me the rubber boy's head!"
Caribou waited for the cheers of his bloodthirsty crew.
He heard nothing. Only the gentle hum of the Sunny's reactor.
Caribou slowly opened one eye.
He looked to his left. No crew.
He looked to his right. No crew.
He looked behind him, out through the bubble. He saw the faint, shrinking speck of his own ship being dragged into the abyss by a terrified cow.
Caribou froze. His sinister smirk completely vanished, replaced by a look of horrifying realization. He slowly turned his head to look at the massive, heavily armed, and highly amused Straw Hat crew surrounding him.
He looked at the four giants cracking their knuckles. He looked at the cyborg powering up a laser. He looked at the swordsman with a demonic aura.
"Oh," Caribou whispered, a single drop of sweat rolling down his face.
His survival instincts kicked in instantly. The murderous pirate persona dissolved. Caribou fell to his knees, clasping his hands together, his face morphing into an expression of pathetic, groveling innocence.
"P-P-Please excuse me!" Caribou stammered, bowing repeatedly. "I seem to have boarded the wrong vessel! A simple navigational error! You wouldn't hit a lost, innocent traveler, would you?!"
"He was just yelling about slaughtering us," Usopp deadpanned.
"How did he get through the bubble?" Nami frowned. "I thought Sunny's automated repulsor shield stopped unauthorized biological entries."
"It does," Ben said, stepping forward from the patio table. He casually slipped his hands into his pockets. "I lowered the shield for exactly two seconds. I allowed him to board."
Caribou blinked, looking up at the Magician. "You... you let me in?"
"I did," Ben nodded. "Because you possess the Numa Numa no Mi. The Swamp-Swamp fruit. A Logia-class ability that creates infinite, bottomless storage space within the user's body. It is a highly useful spatial capability, and I'd very much like to extract the core for my own research."
Caribou's eyes widened in terror. "Extract... my fruit?! What kind of monster are you?!"
Caribou didn't wait to find out. His body instantly liquefied, turning into a bubbling, murky brown swamp as he attempted to sink into the grassy deck and hide within his Logia form. "You'll never catch me! I'm a Logia!"
Ben simply raised his right hand, his index and middle fingers extended.
Ben flicked his wrist.
"Stupefy."
A brilliant, flash-bang of red light erupted from Ben's fingers. It didn't interact with the physical properties of the swamp; it bypassed the Logia state entirely and struck Caribou's soul and nervous system directly.
ZAP!
The spell hit the swamp puddle.
Caribou's body instantly solidified back into his human form. His eyes rolled into the back of his head, and he collapsed onto the deck like a sack of potatoes, completely unconscious, drooling slightly onto the grass.
The entire threat had been neutralized in exactly two seconds.
"Well," Zoro grunted, sheathing his sword slightly. "That was anticlimactic."
"He didn't even get to fight," Luffy pouted, poking the unconscious pirate with his foot.
"He wasn't here to fight. He's here for science," Ben stated smoothly.
Ben raised his hand again to effortlessly levitate Caribou's unconscious body into the air. "I'm going to take him down to the research lab. I need to draw some blood, isolate his DNA sequence, and map the Devil Fruit integration before I extract the template. I'll dump him out an airlock when I'm done."
"Have fun in the lab, Ben," Robin smiled pleasantly as Ben floated the sleeping pirate down the stairs and out of sight.
"Hey Nami!" Luffy turned away from the stairs, walking over to the navigator. He pointed straight down into the dark water. "This is taking forever! Can't Sunny just use the thrusters and go straight down? It would be way faster!"
Nami sighed, shaking her head. She pulled out a large, waterproof map of the deep sea currents she had purchased on Sabaody.
"No, Luffy. We absolutely cannot travel in a straight line," Nami explained, unrolling the map on the table. "The ocean isn't just an empty swimming pool. The deeper we go, the more chaotic the currents become. If we just aim the ship straight down and hit the gas, we would be immediately swallowed by a rogue lateral current. We could be smashed into an underwater volcano, crushed against a sea mountain, or dragged into a kraken nest before we even saw it coming."
Nami traced a specific, winding line on the map. "There is only one safe route to Fishman Island. We have to navigate the natural pathways."
"Indeed," Brook chimed in, adjusting his top hat. "The colder levels of the ocean possess what are known as Deep Currents. They are massive, slow-moving rivers of water that are normally invisible to the naked eye. They move in completely different patterns than the surface currents."
"Invisible rivers?" Usopp adjusted his goggles. "That sounds terrifying."
"It is," Brook nodded solemnly. "I have heard tales that the Deep Currents move so slowly across the ocean floor that if a ship is caught in one, it could take nearly two thousand years for that water to cycle back up to a part of the sea that receives sunlight. We would be trapped in the eternal dark."
"Two thousand years?!" Chopper shrieked, hugging Usopp's leg. "We'd all be skeletons! Except Brook!"
"Yohohoho! Very true!"
"Which is exactly why we aren't driving blindly," Nami reassured them, pointing to a specific point on the map where the currents converged. "In order to reach Fishman Island safely, we need to find a specific oceanic elevator. We need to ride a descending current that bridges the gap between the surface currents and the deep sea currents."
"And how do we find that?" Sanji asked.
Before Nami could answer, a loud, metallic voice called out from the very front of the ship.
"Hey! Everyone!" Franky yelled, leaning far over the bow railing. "Get up here! It's come into view!"
The crew abandoned the map and rushed to the front of the ship, crowding around the lion figurehead.
"What is it, Franky?!" Luffy yelled, climbing onto the lion's head. "Is it a giant meat-monster?!"
Franky didn't pose. He didn't shout "Super". He just pushed his sunglasses down his nose, staring out into the vast, dark expanse of the deep ocean with genuine, unadulterated awe.
"No, bro," Franky murmured. "It's a masterpiece. Marvel at Mother Nature's ultimate creation."
The external floodlights of the Thousand Sunny pierced the murky gloom, illuminating the path ahead.
There, stretching infinitely downward into the lightless abyss, was a colossal, churning pillar of water. It was wider than a city, a massive, spiraling waterfall occurring entirely underwater. The sheer force of the current created a twisting vortex of bubbles and deep-sea debris, humming with a low, terrifying vibration that shook the water around them.
"The great Downward Plume," Franky announced.
The Straw Hats stared at the aquatic titan. It was their elevator to the bottom of the world. And it looked like the mouth of a hungry god.
"We have to go down that?" Usopp whispered, his knees trembling.
Luffy's eyes locked onto the swirling vortex. A massive, fearless grin spread across his face.
"Hold on tight, everybody!" Luffy roared. "Here we go!"